Tighter sync and faster ACK on SwapBuffers/PostSubBuffers

ui/compositor/compositor.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 "ui/compositor/compositor.h"
 
 #include "base/command_line.h"
 #include "base/threading/thread_restrictions.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebCompositor.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebFloatPoint.h"
@@ skipping 113 matching lines @@
 Texture::~Texture() {
 }
 
 Compositor::Compositor(CompositorDelegate* delegate,
                        gfx::AcceleratedWidget widget)
     : delegate_(delegate),
       root_layer_(NULL),
       widget_(widget),
       root_web_layer_(WebKit::WebLayer::create()),
       swap_posted_(false),
-      device_scale_factor_(0.0f) {
+      device_scale_factor_(0.0f),
+      last_started_id_(0),
+      last_will_end_id_(0),
+      last_ended_id_(0) {
   WebKit::WebLayerTreeView::Settings settings;
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   settings.showFPSCounter =
       command_line->HasSwitch(switches::kUIShowFPSCounter);
   settings.showPlatformLayerTree =
       command_line->HasSwitch(switches::kUIShowLayerTree);
   settings.refreshRate = test_compositor_enabled ?
       kTestRefreshRate : kDefaultRefreshRate;
   settings.partialSwapEnabled =
       command_line->HasSwitch(switches::kUIEnablePartialSwap);
@@ skipping 52 matching lines @@
     root_layer_->SetCompositor(this);
   root_web_layer_.removeAllChildren();
   if (root_layer_)
     root_web_layer_.addChild(root_layer_->web_layer());
 }
 
 void Compositor::Draw(bool force_clear) {
   if (!root_layer_)
     return;
 
+  last_started_id_++;
+
   // TODO(nduca): Temporary while compositor calls
   // compositeImmediately() directly.
   layout();
   host_.composite();
+
+  last_will_end_id_++;
+  FOR_EACH_OBSERVER(CompositorObserver,
+                    observer_list_,
+                    OnCompositingWillEnd(this));
+
   if (!g_compositor_thread && !swap_posted_)
     NotifyEnd();
 }
 
 void Compositor::ScheduleFullDraw() {
   host_.setNeedsRedraw();
 }
 
 bool Compositor::ReadPixels(SkBitmap* bitmap,
                             const gfx::Rect& bounds_in_pixel) {
@@ skipping 119 matching lines @@
     memcpy(&pixels[row * row_size],
            &pixels[bitmap_size - (row + 1) * row_size],
            row_size);
     memcpy(&pixels[bitmap_size - (row + 1) * row_size],
            tmp_row.get(),
            row_size);
   }
 }
 
 void Compositor::NotifyEnd() {
+  last_ended_id_++;
   FOR_EACH_OBSERVER(CompositorObserver,
                     observer_list_,
                     OnCompositingEnded(this));
 }
 
 COMPOSITOR_EXPORT void SetupTestCompositor() {
   if (!CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableTestCompositor)) {
     test_compositor_enabled = true;
   }
 #if defined(OS_CHROMEOS)
   // If the test is running on the chromeos envrionment (such as
   // device or vm bots), use the real compositor.
   if (base::chromeos::IsRunningOnChromeOS())
     test_compositor_enabled = false;
 #endif
 }
 
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   test_compositor_enabled = false;
 }
 
 COMPOSITOR_EXPORT bool IsTestCompositorEnabled() {
   return test_compositor_enabled;
 }
 
 }  // namespace ui