Update to Chromium revision 6e53600d (#386251)

- 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.

libcef/browser/browser_context_proxy.cc

@@ -82,7 +82,7 @@ base::FilePath CefBrowserContextProxy::GetPath() const {
   return parent_->GetPath();
 }
 
-scoped_ptr<content::ZoomLevelDelegate>
+std::unique_ptr<content::ZoomLevelDelegate>
     CefBrowserContextProxy::CreateZoomLevelDelegate(
         const base::FilePath& partition_path) {
   return parent_->CreateZoomLevelDelegate(partition_path);
@@ -106,12 +106,6 @@ net::URLRequestContextGetter* CefBrowserContextProxy::GetRequestContext() {
   return GetDefaultStoragePartition(this)->GetURLRequestContext();
 }
 
-net::URLRequestContextGetter*
-    CefBrowserContextProxy::GetRequestContextForRenderProcess(
-        int renderer_child_id) {
-  return GetRequestContext();
-}
-
 net::URLRequestContextGetter*
     CefBrowserContextProxy::GetMediaRequestContext() {
   return GetRequestContext();
@@ -179,6 +173,9 @@ net::URLRequestContextGetter* CefBrowserContextProxy::CreateRequestContext(
     content::URLRequestInterceptorScopedVector request_interceptors) {
   CEF_REQUIRE_UIT();
   DCHECK(!url_request_getter_.get());
+
+  CreateProtocolHandlers(protocol_handlers);
+
   url_request_getter_ =
       new CefURLRequestContextGetterProxy(handler_, parent_->request_context());
   resource_context()->set_url_request_context_getter(url_request_getter_.get());