Enable Canvas2D hardware acceleration for Android WebView

cc/resources/resource_provider.cc

 // Copyright 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 "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
@@ skipping 527 matching lines @@
     DCHECK(gl);
     GLC(gl, gl->DeleteQueriesEXT(1, &resource->gl_upload_query_id));
   }
   if (resource->gl_pixel_buffer_id) {
     GLES2Interface* gl = ContextGL();
     DCHECK(gl);
     GLC(gl, gl->DeleteBuffers(1, &resource->gl_pixel_buffer_id));
   }
   if (resource->mailbox.IsValid() && resource->external) {
     GLuint sync_point = resource->mailbox.sync_point();
-    if (resource->mailbox.IsTexture()) {
+    if (resource->mailbox.IsTexture() && ContextGL() != NULL) {

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

I know I did the same thing in my hack patch, but it is just a hack. We are
leaking resource handles if the context is destroyed but there are still gl
resources left.

       lost_resource |= lost_output_surface_;
       GLES2Interface* gl = ContextGL();
       DCHECK(gl);
       if (resource->gl_id)
         GLC(gl, gl->DeleteTextures(1, &resource->gl_id));
       if (!lost_resource && resource->gl_id)
         sync_point = gl->InsertSyncPointCHROMIUM();
     } else {
       DCHECK(resource->mailbox.IsSharedMemory());
       base::SharedMemory* shared_memory = resource->mailbox.shared_memory();
@@ skipping 1245 matching lines @@
   gl->GetIntegerv(GL_ACTIVE_TEXTURE, &active_unit);
   return active_unit;
 }
 
 GLES2Interface* ResourceProvider::ContextGL() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->ContextGL() : NULL;
 }
 
 }  // namespace cc