cc: Async readback.

cc/output/direct_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/direct_renderer.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/debug/trace_event.h"
+#include "base/hash_tables.h"

[piman, 2013/04/26 00:15:02]

nit: not using this?

 #include "base/metrics/histogram.h"
 #include "cc/base/math_util.h"
 #include "cc/quads/draw_quad.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
 
 static gfx::Transform OrthoProjectionMatrix(float left,
                                             float right,
                                             float bottom,
                                             float top) {
@@ skipping 164 matching lines @@
   const RenderPass* root_render_pass = render_passes_in_draw_order->back();
   DCHECK(root_render_pass);
 
   DrawingFrame frame;
   frame.root_render_pass = root_render_pass;
   frame.root_damage_rect =
       Capabilities().using_partial_swap && client_->AllowPartialSwap() ?
       root_render_pass->damage_rect : root_render_pass->output_rect;
   frame.root_damage_rect.Intersect(gfx::Rect(ViewportSize()));
 
+  std::vector<base::Closure> copy_callbacks;
+
   BeginDrawingFrame(&frame);
-  for (size_t i = 0; i < render_passes_in_draw_order->size(); ++i)
+  for (size_t i = 0; i < render_passes_in_draw_order->size(); ++i) {
     DrawRenderPass(&frame, render_passes_in_draw_order->at(i));
+
+    const RenderPass* pass = frame.current_render_pass;
+    for (size_t i = 0; i < pass->copy_callbacks.size(); ++i) {
+      scoped_ptr<SkBitmap> bitmap(new SkBitmap);
+      CopyCurrentRenderPassToBitmap(&frame, bitmap.get());
+      pass->copy_callbacks[i].Run(bitmap.Pass());
+    }
+  }
   FinishDrawingFrame(&frame);
 
   render_passes_in_draw_order->clear();
 }
 
 gfx::RectF DirectRenderer::ComputeScissorRectForRenderPass(
     const DrawingFrame* frame) {
   gfx::RectF render_pass_scissor = frame->current_render_pass->output_rect;
 
   if (frame->root_damage_rect == frame->root_render_pass->output_rect)
@@ skipping 131 matching lines @@
 gfx::Size DirectRenderer::RenderPassTextureSize(const RenderPass* render_pass) {
   return render_pass->output_rect.size();
 }
 
 // static
 GLenum DirectRenderer::RenderPassTextureFormat(const RenderPass* render_pass) {
   return GL_RGBA;
 }
 
 }  // namespace cc