[WebView] Fix issue with transparent background.

android_webview/browser/hardware_renderer.cc

 // Copyright 2014 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 "android_webview/browser/hardware_renderer.h"
 
 #include "android_webview/browser/aw_gl_surface.h"
 #include "android_webview/browser/deferred_gpu_command_service.h"
 #include "android_webview/browser/parent_output_surface.h"
 #include "android_webview/browser/shared_renderer_state.h"
@@ skipping 77 matching lines @@
   settings.allow_antialiasing = false;
   settings.highp_threshold_min = 2048;
 
   // Webview does not own the surface so should not clear it.
   settings.should_clear_root_render_pass = false;
 
   layer_tree_host_ =
       cc::LayerTreeHost::CreateSingleThreaded(this, this, NULL, settings);
   layer_tree_host_->SetRootLayer(root_layer_);
   layer_tree_host_->SetLayerTreeHostClientReady();
+  layer_tree_host_->set_has_transparent_background(true);
 }
 
 HardwareRenderer::~HardwareRenderer() {
   // Must reset everything before |resource_collection_| to ensure all
   // resources are returned before resetting |resource_collection_| client.
   layer_tree_host_.reset();
   root_layer_ = NULL;
   delegated_layer_ = NULL;
   frame_provider_ = NULL;
   if (resource_collection_.get()) {
@@ skipping 51 matching lines @@
     // physical pixels and set our browser CC device_scale_factor to 1, so this
     // suppresses the transform.
     input->frame.delegated_frame_data->device_scale_factor = 1.0f;
 
     gfx::Size frame_size =
         input->frame.delegated_frame_data->render_pass_list.back()
             ->output_rect.size();
     bool size_changed = frame_size != frame_size_;
     frame_size_ = frame_size;
     scroll_offset_ = input->scroll_offset;
-    layer_tree_host_->set_has_transparent_background(
-        input->has_transparent_background);
 
     if (!frame_provider_ || size_changed) {
       if (delegated_layer_) {
         delegated_layer_->RemoveFromParent();
       }
 
       frame_provider_ = new cc::DelegatedFrameProvider(
           resource_collection_.get(), input->frame.delegated_frame_data.Pass());
 
       delegated_layer_ = cc::DelegatedRendererLayer::Create(frame_provider_);
@@ skipping 44 matching lines @@
 }
 
 void HardwareRenderer::UnusedResourcesAreAvailable() {
   cc::ReturnedResourceArray returned_resources;
   resource_collection_->TakeUnusedResourcesForChildCompositor(
       &returned_resources);
   shared_renderer_state_->InsertReturnedResources(returned_resources);
 }
 
 }  // namespace android_webview