With the introduction of prerendering in Chromium it is now possible for
RenderFrameHosts (RFH) to move between FrameTrees. As a consequence we can no
longer rely on FrameTreeNode IDs to uniquely identify a RFH over its lifespan.
We must now switch to using GlobalRenderFrameHostId (child_id, frame_routing_id)
instead for that purpose. Additionally, we simplify existing code by using the
GlobalRenderFrameHostId struct in all places that previously used a
(render_process_id, render_frame_id) pair, since these concepts are equivalent.
See https://crbug.com/1179502#c8 for additional background.
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.
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.
This change moves the SendProcessMessage method from CefBrowser to CefFrame and
adds CefBrowser parameters to OnProcessMessageReceived and
OnDraggableRegionsChanged.
The internal implementation has changed as follows:
- Frame IDs are now a 64-bit combination of the 32-bit render_process_id and
render_routing_id values that uniquely identify a RenderFrameHost (RFH).
- CefFrameHostImpl objects are now managed by CefBrowserInfo with life span tied
to RFH expectations. Specifically, a CefFrameHostImpl object representing a
sub-frame will be created when a RenderFrame is created in the renderer
process and detached when the associated RenderFrame is deleted or the
renderer process in which it runs has died.
- The CefFrameHostImpl object representing the main frame will always be valid
but the underlying RFH (and associated frame ID) may change over time as a
result of cross-origin navigations. Despite these changes calling LoadURL on
the main frame object in the browser process will always navigate as expected.
- Speculative RFHs, which may be created as a result of a cross-origin
navigation and discarded if that navigation is not committed, are now handled
correctly (e.g. ignored in most cases until they're committed).
- It is less likely, but still possible, to receive a CefFrame object with an
invalid frame ID (ID < 0). This can happen in cases where a RFH has not yet
been created for a sub-frame. For example, when OnBeforeBrowse is called
before initiating navigation in a previously nonexisting sub-frame.
To test: All tests pass with NetworkService enabled and disabled.
- 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.
Marshall Greenblatt