Remove CompositeAndReadback from LayerTreeHost(Impl) and the Proxys.

cc/output/software_renderer.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/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 628 matching lines @@
 }
 
 void SoftwareRenderer::EnsureBackbuffer() {
   if (!is_backbuffer_discarded_)
     return;
 
   output_surface_->EnsureBackbuffer();
   is_backbuffer_discarded_ = false;
 }
 
-void SoftwareRenderer::GetFramebufferPixels(void* pixels,
-                                            const gfx::Rect& rect) {
-  TRACE_EVENT0("cc", "SoftwareRenderer::GetFramebufferPixels");
-  gfx::Rect frame_rect(rect);
-  frame_rect += current_viewport_rect_.OffsetFromOrigin();
-  output_device_->CopyToPixels(frame_rect, pixels);
-}
-
 void SoftwareRenderer::DidChangeVisibility() {
   if (visible())
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 }  // namespace cc