This change adds support for:
- Protocol and request handling.
- Loading and navigation events.
- Display and focus events.
- Mouse/keyboard events.
- Popup browsers.
- Callbacks in the renderer process.
- Misc. functionality required for ceftests.
This change also adds a new CefBrowserProcessHandler::GetCookieableSchemes
callback for configuring global state that will be applied to all
CefCookieManagers by default. This global callback is currently required by the
chrome runtime because the primary ProfileImpl is created via
ChromeBrowserMainParts::PreMainMessageLoopRun (CreatePrimaryProfile) before
OnContextCreated can be called.
ProfileImpl will use the "C:\Users\[user]\AppData\Local\CEF\User Data\Default"
directory by default (on Windows). Cookies may persist in this directory when
running ceftests and may need to be manually deleted if those tests fail.
Remaining work includes:
- Support for client-created request contexts.
- Embedding the browser in a Views hierarchy (cefclient support).
- TryCloseBrowser and DoClose support.
- Most of the CefSettings configuration.
- DevTools protocol and window control (ShowDevTools, ExecuteDevToolsMethod).
- CEF-specific WebUI pages (about, license, webui-hosts).
- Context menu customization (CefContextMenuHandler).
- Auto resize (SetAutoResizeEnabled).
- Zoom settings (SetZoomLevel).
- File dialog runner (RunFileDialog).
- File and JS dialog handlers (CefDialogHandler, CefJSDialogHandler).
- Extension loading (LoadExtension, etc).
- Plugin loading (OnBeforePluginLoad).
- Widevine loading (CefRegisterWidevineCdm).
- PDF and print preview does not display.
- Crash reporting is untested.
- Mac: Web content loads but does not display.
The following ceftests are now passing when run with the
"--enable-chrome-runtime" command-line flag:
CorsTest.*
DisplayTest.*:-DisplayTest.AutoResize
DOMTest.*
DraggableRegionsTest.*
ImageTest.*
MessageRouterTest.*
NavigationTest.*
ParserTest.*
RequestContextTest.*Global*
RequestTest.*
ResourceManagerTest.*
ResourceRequestHandlerTest.*
ResponseTest.*
SchemeHandlerTest.*
ServerTest.*
StreamResourceHandlerTest.*
StreamTest.*
StringTest.*
TaskTest.*
TestServerTest.*
ThreadTest.*
URLRequestTest.*Global*
V8Test.*:-V8Test.OnUncaughtExceptionDevTools
ValuesTest.*
WaitableEventTest.*
XmlReaderTest.*
ZipReaderTest.*
The Browser object represents the top-level Chrome browser window. One or more
tabs (WebContents) are then owned by the Browser object via TabStripModel. A
new Browser object can be created programmatically using "new Browser" or
Browser::Create, or as a result of user action such as dragging a tab out of an
existing window. New or existing tabs can also be added to an already existing
Browser object.
The Browser object acts as the WebContentsDelegate for all attached tabs. CEF
integration requires WebContentsDelegate callbacks and notification of tab
attach/detach. To support this integration we add a cef::BrowserDelegate
(ChromeBrowserDelegate) member that is created in the Browser constructor and
receives delegation for the Browser callbacks. ChromeBrowserDelegate creates a
new ChromeBrowserHostImpl when a tab is added to a Browser for the first time,
and that ChromeBrowserHostImpl continues to exist until the tab's WebContents
is destroyed. The associated WebContents object does not change, but the
Browser object will change when the tab is dragged between windows.
CEF callback logic is shared between the chrome and alloy runtimes where
possible. This shared logic has been extracted from CefBrowserHostImpl to
create new CefBrowserHostBase and CefBrowserContentsDelegate classes. The
CefBrowserHostImpl class is now only used with the alloy runtime and will be
renamed to AlloyBrowserHostImpl in a future commit.
- CefURLRequest::Create is no longer supported in the renderer process
(see https://crbug.com/891872). Use CefFrame::CreateURLRequest instead.
- Mac platform definitions have been changed from `MACOSX` to `MAC`
(see https://crbug.com/1105907) and related CMake macro names have
been updated. The old `OS_MACOSX` define is still set in code and CMake
for backwards compatibility.
- Linux ARM build is currently broken (see https://crbug.com/1123214).
- Windows: 10.0.19041 SDK is now required.
- macOS: 10.15.1 SDK (at least Xcode 11.2) is now required.
- Remove CefMediaSource::IsValid and CefMediaSink::IsValid which would
always return true.
This change moves shared resource initialization to a common location and
disables crash reporting initialization in chrome/ code via patch files.
When using the Chrome runtime on macOS the Chrome application window will
display, but web content is currently blank and the application does not
exit cleanly. This will need to be debugged further in the future.
This change adds basic Chrome runtime implementations for CefBrowserContext
and CefBrowserPlatformDelegate. A Chrome browser window with default frame
and styling can now be created using CefBrowserHost::CreateBrowser and some
CefClient callbacks will be triggered via the WebContentsObserver
implementation in CefBrowserHostImpl.
Any additional browser windows created via the Chrome UI will be unmanaged
by CEF. The application message loop will block until all browser windows
have been closed by the user.
Existing CefBrowserContext functionality is now split between
CefBrowserContext and AlloyBrowserContext. Runtime implementations of
CefBrowserContext will provide access to the content::BrowserContext and
Profile types via different inheritance paths. For example, the Alloy
runtime uses ChromeProfileAlloy and the Chrome runtime uses ProfileImpl.
This change also renames CefResourceContext to CefIOThreadState to more
accurately represent its purpose as it no longer needs to extend
content::ResourceContext.
As part of introducing the Chrome runtime we now need to distinguish
between the classes that implement the current CEF runtime and the
classes the implement the shared CEF library/runtime structure and
public API. We choose the name Alloy for the current CEF runtime
because it describes a combination of Chrome and other elements.
Shared CEF library/runtime classes will continue to use the Cef
prefix. Classes that implement the Alloy or Chrome runtime will use
the Alloy or Chrome prefixes respectively. Classes that extend an
existing Chrome-prefixed class will add the Cef or Alloy suffix,
thereby following the existing naming pattern of Chrome-derived
classes.
This change applies the new naming pattern to an initial set of
runtime-related classes. Additional classes/files will be renamed
and moved as the Chrome runtime implementation progresses.
Running `cefsimple --enable-chrome-runtime` will create and run a
Chrome browser window using the CEF app methods, and call
CefApp::OnContextInitialized as expected. CEF task methods also
work as expected in the main process. No browser-related methods or
callbacks are currently supported for the Chrome window, and the
application will exit when the last Chrome window closes.
The Chrome runtime requires resources.pak, chrome_100_percent.pak
and chrome_200_percent.pak files which were not previously built
with CEF. It shares the existing locales pak files which have been
updated to include additional Chrome-specific strings.
On Linux, the Chrome runtime requires GTK so use_gtk=true must be
specified via GN_DEFINES when building.
This change also refactors the CEF runtime, which can be tested in
the various supported modes by running:
$ cefclient
$ cefclient --multi-threaded-message-loop
$ cefclient --external-message-pump
Split `gclient sync` into separate `gclient sync --nohooks` and
`gclient runhooks` steps so that we can optionally apply patches
from `runhooks.patch` in-between. This is necessary because the
src/tools/clang/scripts/update.py script is run via a hook and has
dependencies on the VS toolchain scripts which must be patched to
properly consider the GYP_MSVS_VERSION environment variable.
This works around a bug in the Visual C++ standard library where the
std::is_integral templates are exported instead of inlined when building
with C++14. See also https://bugs.llvm.org/show_bug.cgi?id=42027.
The PDF loading documentation in extension_system.cc has be updated to
describe the new code paths.
To support delivery of input events to the mime handler renderer process it is
now necessary to route events via the correct RWHV interface. For Aura-based
platforms (Windows/Linux) this means RWHVAura::On*Event and for macOS this
means RWHVMac::RouteOrProcess*Event. Since Aura uses UI event types these have
become the source of truth on Aura-based platforms with conversion to Web event
types when needed (primarily for OSR).
This change also adds a timeout for CefProcessHostMsg_GetNewBrowserInfo to
avoid a hung renderer process if the guest WebContents route is not
registered via CefMimeHandlerViewGuestDelegate::OnGuestDetached as expected
prior to CefBrowserInfoManager::OnGetNewBrowserInfo being called. This
timeout can be disabled for testing purposes by passing the
`--disable-new-browser-info-timeout` command-line flag.
The `--disable-features=MimeHandlerViewInCrossProcessFrame` command-line
flag can be used for a limited time to restore the previous implementation
based on BrowserPlugin. That implementation will be deleted starting with
the 3897 branch update.
Known issues:
- ExecuteJavaScript calls on the frame hosting the PDF extension will not
be routed to the mime handler renderer process.
- The PDF extension will not load successfully if blocked by
ChromePluginPlaceholder and then manually continued via the "Run this
plugin" context menu option (see https://crbug.com/533069#c41).
This works around a bug in the Visual C++ standard library where the
std::is_integral templates are exported instead of inlined when building
with C++14. See also https://bugs.llvm.org/show_bug.cgi?id=42027.
Fixes the following error:
In file included from gen/chrome/browser/safe_browsing/safe_browsing_jumbo_1.cc:34:
In file included from ./../../chrome/browser/safe_browsing/download_protection/binary_fcm_service.cc:15:
../../components/gcm_driver/gcm_profile_service.h:18:10: fatal error: 'components/gcm_driver/gcm_buildflags.h' file not found
When NetworkService is enabled requests created using CefFrame::CreateURLRequest
will call CefRequestHandler::GetAuthCredentials for the associated browser after
calling CefURLRequestClient::GetAuthCredentials if that call returns false.
Requests created using CefURLRequest::Create are not associated with a
browser/frame. When originating from the render process these requests cannot be
intercepted and consequently only http(s) and blob requests are supported. To
work around this limitation a new CefFrame::CreateURLRequest method has been
added that allows the request to be associated with that browser/frame for
interception purposes.
This change also fixes an issue with the NetworkService implementation where
redirected requests could result in two parallel requests being sent to the
target server.
To test: URLRequestTest.* tests pass with NetworkService enabled.
With this change the CefCookieManager::SetSupportedSchemes method can be used
to disable all loading and saving of cookies for the associated request context.
This matches functionality that was previously available via GetBlockingManager.
This change also fixes a bug where Set-Cookie headers returned for a request
handled via CefSchemeHandlerFactory would be ignored if there was not also a
CefResourceRequestHandler returned for the request.
To test: All CookieTest.* tests pass.
To test: When running `cefclient --cache-path=c:\temp\cache` with NetworkService
enabled the the cache directory structure should be "C:\temp\cache\Cache"
instead of "C:\temp\cache\cache\Cache".
When the NetworkService is enabled the U-A string is configured via
SystemNetworkContextManager::CreateDefaultNetworkContextParams, which calls
chrome_content_browser_client.cc GetUserAgent(). This change modifies the Chrome
implementation to match CEF, so that the U-A product component can still be
overridden via the `--product-version` command-line flag.
To test: Verify that chrome://version, navigator.userAgent (JS executed from
DevTools console) and network requests (headers shown in DevTools Network tab)
show the expected User-Agent value in the following cases:
- Running `cefclient --enable-network-service --user-agent="<value>"`
- Running `cefclient --enable-network-service --product-version="<value>"`
To test:
- All tests pass with NetworkService disabled. DownloadTest.*, ExtensionTest.*
and PluginTest.* tests pass with NetworkService enabled.
- The PDF extension displays a file, and the download and print buttons work.
Implementation notes:
- Chromium change: CookieMonster::SetCookieableSchemes needs to be called
immediately after the CookieMonster is created in NetworkContext::
ApplyContextParamsToBuilder. Add a Profile::GetCookieableSchemes method and
NetworkContextParams.cookieable_schemes member (set from
ProfileNetworkContextService::CreateNetworkContextParams) to support that.
- Chromium change: Add a ContentBrowserClient::HandleExternalProtocol variant
that exposes additional NetworkService request information.
- GetResourceResponseFilter is not yet implemented.
API changes:
- Resource-related callbacks have been moved from CefRequestHandler to a new
CefResourceRequestHandler interface which is returned via the
GetResourceRequestHandler method. If the CefRequestHandler declines to handle
a resource it can optionally be handled by the CefRequestContextHandler, if
any, associated with the loading context.
- The OnProtocolExecution callback has been moved from CefRequestHandler to
CefResourceRequestHandler and will be called if a custom scheme request is
unhandled.
- Cookie send/save permission callbacks have been moved from CefRequestHandler
and CefResourceHandler to CefResourceRequestHandler.
- New methods added to CefResourceHandler that better match NetworkService
execution sequence expectations. The old methods are now deprecated.
- New methods added to CefRequest and CefResponse.
Known behavior changes with the NetworkService implementation:
- Modifying the |new_url| parameter in OnResourceRedirect will no longer result
in the method being called an additional time (likely a bug in the old
implementation).
- Modifying the request URL in OnResourceResponse would previously cause a
redirect. This behavior is now deprecated because the NetworkService does not
support this functionality when using default network loaders. Temporary
support has been added in combination with CefResourceHandler usage only.
- Other changes to the request object in OnResourceResponse will now cause the
request to be restarted. This means that OnBeforeResourceLoad, etc, will be
called an additional time with the new request information.
- CefResponse::GetMimeType will now be empty for non-200 responses.
- Requests using custom schemes can now be handled via CefResourceRequestHandler
with the same callback behavior as builtin schemes.
- Redirects of custom scheme requests will now be followed as expected.
- Default handling of builtin schemes can now be disabled by setting
|disable_default_handling| to true in GetResourceRequestHandler.
- Unhandled requests (custom scheme or builtin scheme with default handling
disabled) will fail with an CefResponse::GetError value of
ERR_UNKNOWN_URL_SCHEME.
- The CefSchemeHandlerFactory::Create callback will now include cookie headers.
To test:
- Run `cefclient --enable-network-service`. All resources should load
successfully (this tests the transparent proxy capability).
- All tests pass with NetworkService disabled.
- The following tests pass with NetworkService enabled:
- CookieTest.*
- FrameTest.* (excluding .*Nav)
- NavigationTest.* (excluding .Redirect*)
- RequestHandlerTest.*
- RequestContextTest.Basic*
- RequestContextTest.Popup*
- RequestTest.*
- ResourceManagerTest.*
- ResourceRequestHandlerTest.* (excluding .Filter*)
- SchemeHandlerTest.*
- StreamResourceHandlerTest.*
This adds *.pak, locales/*.pak , chrome-sandbox, libGLESv2.so, libEGL.so and
swiftshader/*.so to the list of binaries that will be loaded from the libcef.so
directory instead of the executable directory by default.
- Windows: 10.0.17763.0 SDK is now required.
- Mac: 10.13 SDK is now required.
- Removed CefRequestContext::ResolveHostCached which is no longer supported by Chromium.
- The |category| value for all TRACE calls from CEF client applications is now
"cef.client" due to https://crrev.com/331266377d.
- The |with_menu_marker| parameter to CreateMenuButton has been removed due to
https://crrev.com/7f7e382118.
- Add CefWindowInfo::shared_texture_enabled and
CefRenderHandler::OnAcceleratedPaint for shared texture support. Currently
only supported on Windows (D3D11).
- Add CefWindowInfo::external_begin_frame_enabled and
CefBrowserHost::SendExternalBeginFrame for external begin frame support.
Known issues:
- The CefLoadCRLSetsFile function needs to be re-implemented (see issue #2497).
- Linux: GTK2 support has been removed. The cefclient sample needs to be updated
to use GTK3 (see issue #2014).
- Add CefRequestContext::LoadExtension, CefExtension, CefExtensionHandler and
related methods/interfaces.
- Add chrome://extensions-support that lists supported Chrome APIs.
- Add CefBrowserHost::SetAutoResizeEnabled and CefDisplayHandler::OnAutoResize
to support browser resize based on preferred web contents size.
- views: Add support for custom CefMenuButton popups.
- cefclient: Run with `--load-extension=set_page_color` command-line flag for
an extension loading example. Add `--use-views` on Windows and Linux for an
even better example.
- Crash reporting is enabled and configured using a "crash_reporter.cfg"
file. See comments in include/cef_crash_util.h and tools/crash_server.py
for usage.
- Don't set InitParams::TRANSLUCENT_WINDOW. Setting this resulted in
the WS_EX_COMPOSITED style being added and the WS_THICKFRAME style
being removed, which disabled Aero Snap.
- Remove the non-client border to get a completely frameless window.
Having a border is problematic because the top is drawn by Windows
while the rest is drawn black. Having Windows draw part of the
border is required to enable the window drop shadow (see
HWNDMessageHandler::SetDwmFrameExtension).
- Delete the remove_caption patches which are no longer required.
- Net security (CT, HSTS) expiration based on build age is now
disabled by default.
- Add new enable_net_security_expiration option to CefSettings and
CefRequestContextSettings.
- Simplify usage of OnBeforePluginLoad (issue #2015)
- Switch crash reporting from crashpad to breakpad on Windows and OS X.
Adds a new chrome_elf.dll dependency on Windows (issue #1995)
- Remove CefTextfield::GetPlaceholderTextColor() method which is no
longer supported by Chromium.
- Remove |accept_lang| parameter from CefJSDialogHandler::OnJSDialog
and CefFormatUrlForSecurityDisplay (see https://crbug.com/336973#c36).
- Remove remaining NPAPI-related code including functions from
cef_web_plugin.h (see https://crbug.com/493212#c55).
- Mac: 10.7+ deployment target is now required for client applications.
- Mac: Remove CefBrowserHost::SetWindowVisibility (issue #1375). No
replacement is required for windowed rendering. Use WasHidden for
off-screen rendering.
- Windows: Visual Studio 2015 Update 2 is now required when building
CEF/Chromium.
- Add Views header files in a new include/views directory.
- Add initial top-level window (CefWindow), control (CefBrowserView,
CefLabelButton, CefMenuButton, CefPanel, CefScrollView,
CefTextfield) and layout (CefBoxLayout, CefFlowLayout) support.
See libcef/browser/views/view_impl.h comments for implementation
details.
- Add Views example usage in cefclient and cefsimple and Views unit
tests in cef_unittests. Pass the `--use-views` command-line flag to
cefclient, cefsimple and cef_unittests to run using the Views
framework instead of platform APIs. For cefclient and cefsimple
this will create the browser window and all related functionality
using the Views framework. For cef_unittests this will run all
tests (except OSR tests) in a Views-based browser window. Views-
specific unit tests (`--gtest_filter=Views*`) will be run even if
the the `--use-views` flag is not specified.
- Pass the `--hide-frame` command-line flag to cefclient to demo a
frameless Views-based browser window.
- Pass the `--hide-controls` command-line flag to cefclient to demo a
browser window without top controls. This also works in non-Views
mode.
- Pass the `--enable-high-dpi-support` command-line flag to
cef_unittests on Windows to test high-DPI support on a display
that supports it.
- Add CefImage for reading/writing image file formats.
- Add CefBrowser::DownloadImage() for downloading image URLs as a
CefImage representation. This is primarily for loading favicons.
- Add CefMenuModel::CreateMenuModel() and CefMenuModelDelegate for
creating custom menus. This is primarily for use with
CefMenuButton.
- Add CefBrowser::TryCloseBrowser() helper for closing a browser.
Also improve related documentation in cef_life_span_handler.h.
- Rename cef_page_range_t to cef_range_t. It is now also used by
CefTextfield.
- Remove CefLifeSpanHandler::RunModal() which is never called.
- Add draggable regions example to cefclient.
- Delete include/cef_runnable.h (issue #1336).
- Build the cef_unittests target using all Chromium headers. Add a
USING_CHROMIUM_INCLUDES define and libcef_dll_wrapper_unittests
target to support this. This change avoids compile errors due to
the divergence of CEF and Chromium base/ header implementations.
The libcef_dll_wrapper sources must now compile successfully with
both CEF and Chromium base/ headers (issue #1632).
- The onbeforeunload message specified via JavaScript is no longer
passed to the client (see http://crbug.com/587940).
- Building on Windows now requires the Windows 10.0.10586 SDK.
- Remove CefParseCSSColor which was implemented using Blink code in the
browser process. This is longer advisable now that the Oilpan GC is enabled.
- Avoid potential renderer process crashes by disabling script actions
on the CefV8Context passed to CefRenderProcessHandler::OnContextReleased.
- Improve ordering of CefLoadHandler callbacks. OnLoadingStateChange will
be called before and after all calls to OnLoadStart and OnLoadEnd.
OnLoadStart/OnLoadEnd calls will occur as matching pairs
(see http://crbug.com/539952#c2).
- Remove the |requesting_url| argument to CefGeolocationHandler::
OnCancelGeolocationPermission. Clients can use the |request_id| argument
to track this information themselves.
- Fix a crash when loading the PDF extension in multiple browsers with a
custom CefRequestContext (issue #1757).
- Persist modified user preferences including per-host zoom settings when a
cache_path value is specified and persist_user_preferences is set to true
via CefSettings or CefRequestContextSettings.
- Avoid the need to duplicate files from chrome/ by having CefBrowserContext
extend Chrome's Profile class.
- Implement CefRequestHandler::OnBeforeBrowse using NavigationThrottle
instead of ResourceThrottle (see http://crbug.com/537634). The CefRequest
object passed to OnBeforeBrowse will no longer have an associated request
identifier.
- Mac: Remove additional helper apps which are no longer required (see
http://crbug.com/520680)
- Remove the UR_FLAG_REPORT_RAW_HEADERS flag which is no longer supported (see
http://crbug.com/517114)
- Remove the CefBrowserSettings.java parameter. Java is an NPAPI plugin and
NPAPI plugins are no longer supported (see http://crbug.com/470301#c11)
- Add CefFormatUrlForSecurityDisplay function in cef_parser.h
- Fix crash when passing `--disable-extensions` command-line flag (issue #1721)
- Linux: Fix NSS handler loading (issue #1727)
- Mac: 10.10 SDK is now required for building (see http://crbug.com/463170#c63).
Older SDKs can be used for a short time by setting mac_sdk_min via GYP_DEFINES.
A system-wide installation of the Pepper Flash plugin is available from Adobe
for Windows and Mac OS X platforms as a separate download. To enable automatic
detection and loading of the system-wide installation pass the
`--enable-system-flash` command-line flag.
The Pepper Flash plugin can also be loaded by specifying the file path and
version via the `--ppapi-flash-path=<path> --ppapi-flash-version=<version>`
command-line flags. The version can be identified by viewing the
manifest.json file in the same directory as the Pepper Flash plugin library.
- Add a new CefRequestHandler::OnResourceResponse() method for inspecting the request/response headers and potentially restarting or redirecting the request.
- Add a new CefRequest::GetIdentifier() method for tracking a request across multiple CefRequestHandler callbacks.
- Pass a CefRequest object instead of just the old URL to CefRequestHandler::OnResourceRedirect().
git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@2073 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
- CefRequestContext instances can be configured using a new CefRequestContextSettings structure passed to CefRequestContext::CreateContext.
- Scheme registration is now per-request-context using new CefRequestContext::RegisterSchemeHandlerFactory and ClearSchemeHandlerFactories methods.
- Cookie managers are now per-request-context by default and can be retrieved using a new CefRequestContext::GetDefaultCookieManager method.
- CefURLRequest::Create now accepts an optional CefRequestContext argument for associating a URL request with a context (browser process only).
- The CefRequestContextHandler associated with a CefRequestContext will not be released until all objects related to that context have been destroyed.
- When the cache path is empty an in-memory cache ("incognito mode") will be used for storage and no data will be persisted to disk.
- Add CefSettings.user_data_path which specifies the location where user data such as spell checking dictionary files will be stored on disk.
- Add asynchronous callbacks for all CefCookieManager methods.
- Add PK_LOCAL_APP_DATA and PK_USER_DATA path keys for retrieving user directories via CefGetPath.
- cefclient: Add "New Window" test that creates a new window unrelated to existing windows. When used in combination with `--request-context-per-browser` the new window will be given a new and isolated request context.
git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@2040 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
- Always set the browser process VSync rate (frame rate) to CefSettings.windowless_frame_rate.
- When the `enable-begin-frame-scheduling` command-line flag is specified the VSync rate for all processes will be synchronized to CefSettings.windowless_frame_rate. This flag cannot be used in combination with windowed rendering.
- When the `disable-gpu` and `disable-gpu-compositing` command-line flags are specified the CefRenderHandler::OnPaint method will be called directly from the compositor instead of requiring an additional copy for each frame.
- CefRenderHandler::OnPopupSize now passes view coordinates instead of (potentially scaled) pixel coordinates.
- Add OSR unit tests for 2x (HiDPI) pixel scaling.
- Improve CefRenderHandler documentation.
git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@1960 5089003a-bbd8-11dd-ad1f-f1f9622dbc98