cc: Invalidate framebuffer contents when clearing

cc/trees/layer_tree_host.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 "cc/trees/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 
 #include "base/bind.h"
@@ skipping 38 matching lines @@
 RendererCapabilities::RendererCapabilities()
     : best_texture_format(0),
       using_partial_swap(false),
       using_set_visibility(false),
       using_egl_image(false),
       allow_partial_texture_updates(false),
       using_offscreen_context3d(false),
       max_texture_size(0),
       avoid_pow2_textures(false),
       using_map_image(false),
-      using_shared_memory_resources(false) {}
+      using_shared_memory_resources(false),
+      using_discard_framebuffer(false) {}
 
 RendererCapabilities::~RendererCapabilities() {}
 
 UIResourceRequest::UIResourceRequest()
     : type(UIResourceInvalidRequest), id(0), bitmap(NULL) {}
 
 UIResourceRequest::~UIResourceRequest() {}
 
 bool LayerTreeHost::AnyLayerTreeHostInstanceExists() {
   return s_num_layer_tree_instances > 0;
@@ skipping 1120 matching lines @@
 void LayerTreeHost::DidLoseUIResources() {
   // When output surface is lost, we need to recreate the resource.
   for (UIResourceClientMap::iterator iter = ui_resource_client_map_.begin();
        iter != ui_resource_client_map_.end();
        ++iter) {
     UIResourceLost(iter->first);
   }
 }
 
 }  // namespace cc