Enable Canvas2D hardware acceleration for Android WebView

webkit/renderer/compositor_bindings/web_external_texture_layer_impl.cc

 // Copyright 2011 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 "webkit/renderer/compositor_bindings/web_external_texture_layer_impl.h"
 
 #include "cc/layers/texture_layer.h"
 #include "cc/resources/resource_update_queue.h"
 #include "cc/resources/single_release_callback.h"
 #include "cc/resources/texture_mailbox.h"
@@ skipping 64 matching lines @@
 
   if (use_shared_memory)
     bitmap = AllocateBitmap();
   if (!client_->prepareMailbox(&client_mailbox, bitmap)) {
     if (bitmap)
       free_bitmaps_.push_back(bitmap);
     return false;
   }
   gpu::Mailbox name;
   name.SetName(client_mailbox.name);
-  if (bitmap)
+  if (bitmap && name.IsZero())

[boliu, 2014/01/06 18:16:13]

This is patching over another issue which I hacked around here:
https://codereview.chromium.org/124063003/diff/60001/cc/trees/layer_tree_host.cc

The right fix is that if we are in hardware canvas2d, then bitmap should be
false.

     *mailbox = cc::TextureMailbox(bitmap->shared_memory(), bitmap->size());
   else
     *mailbox = cc::TextureMailbox(name, client_mailbox.syncPoint);
 
   if (mailbox->IsValid()) {
     *release_callback = cc::SingleReleaseCallback::Create(base::Bind(
         &WebExternalTextureLayerImpl::DidReleaseMailbox,
         this->AsWeakPtr(),
         client_mailbox,
         bitmap));
@@ skipping 25 matching lines @@
 
   blink::WebExternalTextureMailbox available_mailbox;
   memcpy(available_mailbox.name, mailbox.name, sizeof(available_mailbox.name));
   available_mailbox.syncPoint = sync_point;
   if (bitmap)
     layer->free_bitmaps_.push_back(bitmap);
   layer->client_->mailboxReleased(available_mailbox);
 }
 
 }  // namespace webkit