cc: Add CopyAsBitmapRequest class to hold the readback callback.

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 857 matching lines @@
   RenderingStats* stats_ptr =
       debug_state_.RecordRenderingStats() ? &stats : NULL;
 
   in_paint_layer_contents_ = true;
 
   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list);
   for (LayerIteratorType it =
            LayerIteratorType::Begin(&render_surface_layer_list);
        it != end;
        ++it) {
-    bool prevent_occlusion =
-        it.target_render_surface_layer()->HasRequestCopyCallback();
+    bool prevent_occlusion = it.target_render_surface_layer()->HasCopyRequest();
     occlusion_tracker.EnterLayer(it, prevent_occlusion);
 
     if (it.represents_target_render_surface()) {
       DCHECK(it->render_surface()->draw_opacity() ||
              it->render_surface()->draw_opacity_is_animating());
       need_more_updates |= PaintMasksForRenderSurface(*it, queue, stats_ptr);
     } else if (it.represents_itself()) {
       DCHECK(!it->paint_properties().bounds.IsEmpty());
       it->Update(queue, &occlusion_tracker, stats_ptr);
       need_more_updates |= it->NeedMoreUpdates();
@@ skipping 127 matching lines @@
     bool start_ready_animations = true;
     (*iter).second->UpdateState(start_ready_animations, NULL);
   }
 }
 
 skia::RefPtr<SkPicture> LayerTreeHost::CapturePicture() {
   return proxy_->CapturePicture();
 }
 
 }  // namespace cc