Revert of Make CompositorImpl::CompositeAndReadback fail and return false.

content/browser/renderer_host/compositor_impl_android.cc

 // Copyright (c) 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 "content/browser/renderer_host/compositor_impl_android.h"
 
 #include <android/bitmap.h>
 #include <android/native_window_jni.h>
 
 #include "base/android/jni_android.h"
@@ skipping 350 matching lines @@
   root_layer_->SetBounds(size);
 }
 
 void CompositorImpl::SetHasTransparentBackground(bool flag) {
   has_transparent_background_ = flag;
   if (host_)
     host_->set_has_transparent_background(flag);
 }
 
 bool CompositorImpl::CompositeAndReadback(void *pixels, const gfx::Rect& rect) {
-  return false;
+  if (host_)
+    return host_->CompositeAndReadback(pixels, rect);
+  else
+    return false;
 }
 
 cc::UIResourceId CompositorImpl::GenerateUIResourceFromUIResourceBitmap(
     const cc::UIResourceBitmap& bitmap,
     bool is_transient) {
   if (!host_)
     return 0;
 
   cc::UIResourceId id = 0;
   scoped_ptr<cc::UIResourceClient> resource;
@@ skipping 132 matching lines @@
 
 void CompositorImpl::DidCommit() {
   root_window_->OnCompositingDidCommit();
 }
 
 void CompositorImpl::AttachLayerForReadback(scoped_refptr<cc::Layer> layer) {
   root_layer_->AddChild(layer);
 }
 
 }  // namespace content