Very basic Android browser-side compositing support.

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 1351 matching lines @@
 
 void WebContentsImpl::RequestMediaAccessPermission(
     const content::MediaStreamRequest* request,
     const content::MediaResponseCallback& callback) {
   if (delegate_)
     delegate_->RequestMediaAccessPermission(this, request, callback);
   else
     callback.Run(content::MediaStreamDevices());
 }
 
+void WebContentsImpl::AttachLayer(WebKit::WebLayer& layer) {
+  if (delegate_)
+    delegate_->AttachLayer(this, layer);

[klobag.chromium, 2012/08/22 07:01:19]

Isn't this assume WebContentsImpl only have one WebLayer?

WebContentsImpl uses RenderViewHostManager to manage the RenderWidgetHost. We
need to be careful of this.

[no sievers, 2012/08/22 21:17:40]

It could end up adding more than one theoretically, but since I set
drawsContent() to true/false in RWHVA::Show()/Hide(), only one should render at
any given time.

+}
+
+void WebContentsImpl::RemoveLayer(WebKit::WebLayer& layer) {
+  if (delegate_)
+    delegate_->RemoveLayer(this, layer);
+}
+
 void WebContentsImpl::UpdatePreferredSize(const gfx::Size& pref_size) {
   preferred_size_ = pref_size;
   if (delegate_)
     delegate_->UpdatePreferredSize(this, pref_size);
 }
 
 void WebContentsImpl::ResizeDueToAutoResize(const gfx::Size& new_size) {
   if (delegate_)
     delegate_->ResizeDueToAutoResize(this, new_size);
 }
@@ skipping 1753 matching lines @@
       old_browser_plugin_host()->embedder_render_process_host();
   *embedder_container_id = old_browser_plugin_host()->instance_id();
   int embedder_process_id =
       embedder_render_process_host ? embedder_render_process_host->GetID() : -1;
   if (embedder_process_id != -1) {
     *embedder_channel_name =
         StringPrintf("%d.r%d", render_view_host->GetProcess()->GetID(),
                      embedder_process_id);
   }
 }