Plumb the partial swap though image transport.

Plumbs the partial swap through on platforms that support it (currently just Linux GLX).

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/8513013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111392 0039d316-1c4b-4281-b951-d872f2087c98

23 files changed, 288 insertions, 46 deletions

diff --git a/content/browser/gpu/gpu_process_host_ui_shim.cc b/content/browser/gpu/gpu_process_host_ui_shim.cc
index 503a429..e7bda6d 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.cc
+++ b/content/browser/gpu/gpu_process_host_ui_shim.cc
@@ -174,6 +174,8 @@ bool GpuProcessHostUIShim::OnControlMessageReceived(
 
     IPC_MESSAGE_HANDLER(GpuHostMsg_AcceleratedSurfaceBuffersSwapped,
                         OnAcceleratedSurfaceBuffersSwapped)
+    IPC_MESSAGE_HANDLER(GpuHostMsg_AcceleratedSurfacePostSubBuffer,
+                        OnAcceleratedSurfacePostSubBuffer)
 
 #if defined(TOOLKIT_USES_GTK) || defined(OS_WIN)
     IPC_MESSAGE_HANDLER(GpuHostMsg_ResizeView, OnResizeView)
@@ -340,6 +342,30 @@ void GpuProcessHostUIShim::OnAcceleratedSurfaceBuffersSwapped(
   view->AcceleratedSurfaceBuffersSwapped(params, host_id_);
 }
 
+void GpuProcessHostUIShim::OnAcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params) {
+  TRACE_EVENT0("renderer",
+      "GpuProcessHostUIShim::OnAcceleratedSurfacePostSubBuffer");
+
+  ScopedSendOnIOThread delayed_send(
+      host_id_,
+      new AcceleratedSurfaceMsg_PostSubBufferACK(params.route_id));
+
+  RenderViewHost* host = RenderViewHost::FromID(params.renderer_id,
+                                                params.render_view_id);
+  if (!host)
+    return;
+
+  RenderWidgetHostView* view = host->view();
+  if (!view)
+    return;
+
+  delayed_send.Cancel();
+
+  // View must send ACK message after next composite.
+  view->AcceleratedSurfacePostSubBuffer(params, host_id_);
+}
+
 #if defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
 
 void GpuProcessHostUIShim::OnAcceleratedSurfaceRelease(
diff --git a/content/browser/gpu/gpu_process_host_ui_shim.h b/content/browser/gpu/gpu_process_host_ui_shim.h
index d4f566f..b274bad 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.h
+++ b/content/browser/gpu/gpu_process_host_ui_shim.h
@@ -22,6 +22,7 @@
 #include "content/common/message_router.h"
 
 struct GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params;
+struct GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params;
 struct GpuHostMsg_AcceleratedSurfaceNew_Params;
 struct GpuHostMsg_AcceleratedSurfaceRelease_Params;
 
@@ -96,6 +97,8 @@ class GpuProcessHostUIShim
 
   void OnAcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params);
+  void OnAcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params);
 
 #if defined(OS_MACOSX) || defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
   void OnAcceleratedSurfaceNew(
diff --git a/content/browser/renderer_host/render_widget_host.cc b/content/browser/renderer_host/render_widget_host.cc
index 6da29ab..1eeb8e8 100644
--- a/content/browser/renderer_host/render_widget_host.cc
+++ b/content/browser/renderer_host/render_widget_host.cc
@@ -1479,9 +1479,18 @@ bool RenderWidgetHost::GotResponseToLockMouseRequest(bool allowed) {
 }
 
 #if defined(OS_MACOSX) || defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
+// static
 void RenderWidgetHost::AcknowledgeSwapBuffers(int32 route_id, int gpu_host_id) {
   GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
   if (ui_shim)
     ui_shim->Send(new AcceleratedSurfaceMsg_BuffersSwappedACK(route_id));
 }
+
+// static
+void RenderWidgetHost::AcknowledgePostSubBuffer(int32 route_id,
+                                                int gpu_host_id) {
+  GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
+  if (ui_shim)
+    ui_shim->Send(new AcceleratedSurfaceMsg_PostSubBufferACK(route_id));
+}
 #endif
diff --git a/content/browser/renderer_host/render_widget_host.h b/content/browser/renderer_host/render_widget_host.h
index 2ed1e50..71db8b7 100644
--- a/content/browser/renderer_host/render_widget_host.h
+++ b/content/browser/renderer_host/render_widget_host.h
@@ -443,7 +443,8 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Channel::Listener,
 
 #if defined(OS_MACOSX) || defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
   // Called by the view in response to AcceleratedSurfaceBuffersSwapped.
-  void AcknowledgeSwapBuffers(int32 route_id, int gpu_host_id);
+  static void AcknowledgeSwapBuffers(int32 route_id, int gpu_host_id);
+  static void AcknowledgePostSubBuffer(int32 route_id, int gpu_host_id);
 #endif
 
  protected:
diff --git a/content/browser/renderer_host/render_widget_host_view.h b/content/browser/renderer_host/render_widget_host_view.h
index 44a8427..6ed0974 100644
--- a/content/browser/renderer_host/render_widget_host_view.h
+++ b/content/browser/renderer_host/render_widget_host_view.h
@@ -27,6 +27,7 @@
 #include "ui/gfx/surface/transport_dib.h"
 
 struct GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params;
+struct GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params;
 
 class BackingStore;
 class RenderWidgetHost;
@@ -197,6 +198,11 @@ class RenderWidgetHostView {
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) = 0;
+  // Similar to above, except |params.(x|y|width|height)| define the region
+  // of the surface that changed.
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) = 0;
 
 #if defined(OS_MACOSX)
   // Tells the view whether or not to accept first responder status.  If |flag|
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 62b1d27e..3dbf572 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -277,8 +277,8 @@ void RenderWidgetHostViewAura::OnAcceleratedCompositingStateChange() {
 }
 
 void RenderWidgetHostViewAura::AcceleratedSurfaceBuffersSwapped(
-      const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
-      int gpu_host_id) {
+    const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
+    int gpu_host_id) {
 #if defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
   window_->layer()->SetExternalTexture(
       accelerated_surface_containers_[params.surface_id]->GetTexture());
@@ -287,14 +287,44 @@ void RenderWidgetHostViewAura::AcceleratedSurfaceBuffersSwapped(
   if (!window_->layer()->GetCompositor()) {
     // We have no compositor, so we have no way to display the surface.
     // Must still send the ACK.
-    host_->AcknowledgeSwapBuffers(params.route_id, gpu_host_id);
+    RenderWidgetHost::AcknowledgeSwapBuffers(params.route_id, gpu_host_id);
   } else {
     window_->layer()->ScheduleDraw();
 
     // Add sending an ACK to the list of things to do OnCompositingEnded
     on_compositing_ended_callbacks_.push_back(
         base::Bind(&RenderWidgetHost::AcknowledgeSwapBuffers,
-                   base::Unretained(host_), params.route_id, gpu_host_id));
+                   params.route_id, gpu_host_id));
+    ui::Compositor* compositor = window_->layer()->GetCompositor();
+    if (!compositor->HasObserver(this))
+      compositor->AddObserver(this);
+  }
+#else
+  NOTREACHED();
+#endif
+}
+
+void RenderWidgetHostViewAura::AcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+    int gpu_host_id) {
+#if defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
+  window_->layer()->SetExternalTexture(
+      accelerated_surface_containers_[params.surface_id]->GetTexture());
+  glFlush();
+
+  if (!window_->layer()->GetCompositor()) {
+    // We have no compositor, so we have no way to display the surface
+    // Must still send the ACK
+    RenderWidgetHost::AcknowledgePostSubBuffer(params.route_id, gpu_host_id);
+  } else {
+    // TODO(backer): Plumb the damage rect to the ui compositor so that we
+    // can do a partial swap to display.
+    window_->layer()->ScheduleDraw();
+
+    // Add sending an ACK to the list of things to do OnCompositingEnded
+    on_compositing_ended_callbacks_.push_back(
+        base::Bind(&RenderWidgetHost::AcknowledgePostSubBuffer,
+                   params.route_id, gpu_host_id));
     ui::Compositor* compositor = window_->layer()->GetCompositor();
     if (!compositor->HasObserver(this))
       compositor->AddObserver(this);
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index 3bef8a3..3e256dc 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -74,6 +74,9 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) OVERRIDE;
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) OVERRIDE;
 #if defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
   virtual void AcceleratedSurfaceNew(
       int32 width,
diff --git a/content/browser/renderer_host/render_widget_host_view_gtk.cc b/content/browser/renderer_host/render_widget_host_view_gtk.cc
index 100c48a..b014f6a 100644
--- a/content/browser/renderer_host/render_widget_host_view_gtk.cc
+++ b/content/browser/renderer_host/render_widget_host_view_gtk.cc
@@ -1011,6 +1011,12 @@ void RenderWidgetHostViewGtk::AcceleratedSurfaceBuffersSwapped(
   NOTREACHED();
 }
 
+void RenderWidgetHostViewGtk::AcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+    int gpu_host_id) {
+  NOTREACHED();
+}
+
 void RenderWidgetHostViewGtk::SetBackground(const SkBitmap& background) {
   RenderWidgetHostView::SetBackground(background);
   host_->Send(new ViewMsg_SetBackground(host_->routing_id(), background));
diff --git a/content/browser/renderer_host/render_widget_host_view_gtk.h b/content/browser/renderer_host/render_widget_host_view_gtk.h
index 39837e5..8eb1a29 100644
--- a/content/browser/renderer_host/render_widget_host_view_gtk.h
+++ b/content/browser/renderer_host/render_widget_host_view_gtk.h
@@ -98,6 +98,9 @@ class CONTENT_EXPORT RenderWidgetHostViewGtk : public RenderWidgetHostView,
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) OVERRIDE;
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) OVERRIDE;
   virtual void SetBackground(const SkBitmap& background) OVERRIDE;
   virtual void CreatePluginContainer(gfx::PluginWindowHandle id) OVERRIDE;
   virtual void DestroyPluginContainer(gfx::PluginWindowHandle id) OVERRIDE;
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 5726aa7..aad12de 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -260,6 +260,9 @@ class RenderWidgetHostViewMac : public RenderWidgetHostView {
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) OVERRIDE;
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) OVERRIDE;
   virtual void GetScreenInfo(WebKit::WebScreenInfo* results) OVERRIDE;
   virtual gfx::Rect GetRootWindowBounds() OVERRIDE;
   virtual gfx::PluginWindowHandle GetCompositingSurface() OVERRIDE;
@@ -305,12 +308,6 @@ class RenderWidgetHostViewMac : public RenderWidgetHostView {
   // should be called after the software backing store has been painted to.
   void HandleDelayedGpuViewHiding();
 
-  // This is called from the display link thread, and provides the GPU
-  // process a notion of how quickly the browser is able to keep up with it.
-  void AcknowledgeSwapBuffers(int renderer_id,
-                              int32 route_id,
-                              int gpu_host_id);
-
   // These member variables should be private, but the associated ObjC class
   // needs access to them and can't be made a friend.
 
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 3300a41..46a5c4f6 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -884,13 +884,17 @@ void RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped(
     [view drawView];
   }
 
-  if (params.renderer_id != 0 || params.route_id != 0) {
-    AcknowledgeSwapBuffers(params.renderer_id,
-                           params.route_id,
-                           gpu_host_id);
+  if (params.route_id != 0) {
+    RenderWidgetHost::AcknowledgeSwapBuffers(params.route_id, gpu_host_id);
   }
 }
 
+void RenderWidgetHostViewMac::AcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+    int gpu_host_id) {
+  NOTIMPLEMENTED();
+}
+
 void RenderWidgetHostViewMac::UpdateRootGpuViewVisibility(
     bool show_gpu_widget) {
   // Plugins are destroyed on page navigate. The compositor layer on the other
@@ -920,26 +924,6 @@ void RenderWidgetHostViewMac::HandleDelayedGpuViewHiding() {
   }
 }
 
-void RenderWidgetHostViewMac::AcknowledgeSwapBuffers(
-    int renderer_id,
-    int32 route_id,
-    int gpu_host_id) {
-  TRACE_EVENT0("gpu", "RenderWidgetHostViewMac::AcknowledgeSwapBuffers");
-  // Called on the display link thread. Hand actual work off to the IO thread,
-  // because |GpuProcessHost::Get()| can only be called there.
-  // Currently, this is never called for plugins.
-  if (render_widget_host_) {
-    DCHECK_EQ(render_widget_host_->process()->GetID(), renderer_id);
-    // |render_widget_host_->routing_id()| and |route_id| are usually not
-    // equal: The former identifies the channel from the RWH in the browser
-    // process to the corresponding render widget in the renderer process, while
-    // the latter identifies the channel from the GpuCommandBufferStub in the
-    // GPU process to the corresponding command buffer client in the renderer.
-    
-    render_widget_host_->AcknowledgeSwapBuffers(route_id, gpu_host_id);
-  }
-}
-
 void RenderWidgetHostViewMac::OnAcceleratedCompositingStateChange() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   bool activated = GetRenderWidgetHost()->is_accelerated_compositing_active();
diff --git a/content/browser/renderer_host/render_widget_host_view_win.cc b/content/browser/renderer_host/render_widget_host_view_win.cc
index d8c85df..2eecc7f 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.cc
+++ b/content/browser/renderer_host/render_widget_host_view_win.cc
@@ -2102,6 +2102,12 @@ void RenderWidgetHostViewWin::AcceleratedSurfaceBuffersSwapped(
                  acknowledge_task));
 }
 
+void RenderWidgetHostViewWin::AcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+    int gpu_host_id) {
+  NOTREACHED();
+}
+
 void RenderWidgetHostViewWin::SetAccessibilityFocus(int acc_obj_id) {
   if (!render_widget_host_)
     return;
diff --git a/content/browser/renderer_host/render_widget_host_view_win.h b/content/browser/renderer_host/render_widget_host_view_win.h
index b55e7cc..d0fa783 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.h
+++ b/content/browser/renderer_host/render_widget_host_view_win.h
@@ -205,6 +205,9 @@ class RenderWidgetHostViewWin
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) OVERRIDE;
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) OVERRIDE;
   virtual void OnAccessibilityNotifications(
       const std::vector<ViewHostMsg_AccessibilityNotification_Params>& params
       ) OVERRIDE;
diff --git a/content/browser/renderer_host/test_render_view_host.cc b/content/browser/renderer_host/test_render_view_host.cc
index 0524288..9647381 100644
--- a/content/browser/renderer_host/test_render_view_host.cc
+++ b/content/browser/renderer_host/test_render_view_host.cc
@@ -184,6 +184,11 @@ void TestRenderWidgetHostView::AcceleratedSurfaceBuffersSwapped(
     int gpu_host_id) {
 }
 
+void TestRenderWidgetHostView::AcceleratedSurfacePostSubBuffer(
+    const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+    int gpu_host_id) {
+}
+
 #if defined(OS_MACOSX)
 
 gfx::Rect TestRenderWidgetHostView::GetViewCocoaBounds() const {
diff --git a/content/browser/renderer_host/test_render_view_host.h b/content/browser/renderer_host/test_render_view_host.h
index 8e1462b..ebfe62f 100644
--- a/content/browser/renderer_host/test_render_view_host.h
+++ b/content/browser/renderer_host/test_render_view_host.h
@@ -92,6 +92,9 @@ class TestRenderWidgetHostView : public RenderWidgetHostView {
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) OVERRIDE;
+  virtual void AcceleratedSurfacePostSubBuffer(
+      const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
+      int gpu_host_id) OVERRIDE;
 #if defined(OS_MACOSX)
   virtual void SetTakesFocusOnlyOnMouseDown(bool flag) OVERRIDE {}
   virtual gfx::Rect GetViewCocoaBounds() const OVERRIDE;
@@ -136,10 +139,6 @@ class TestRenderWidgetHostView : public RenderWidgetHostView {
   virtual void AcceleratedSurfaceNew(
       int32 width, int32 height, uint64* surface_id,
       TransportDIB::Handle* surface_handle) { }
-  virtual void AcceleratedSurfaceBuffersSwapped(
-      uint64 surface_id,
-      int32 route_id,
-      int gpu_host_id) OVERRIDE {}
   virtual void AcceleratedSurfaceRelease(uint64 surface_id) { }
 #endif
 
diff --git a/content/common/gpu/gpu_messages.h b/content/common/gpu/gpu_messages.h
index 8c99041..e5cab60 100644
--- a/content/common/gpu/gpu_messages.h
+++ b/content/common/gpu/gpu_messages.h
@@ -58,6 +58,20 @@ IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params)
 #endif
 IPC_STRUCT_END()
 
+IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params)
+  IPC_STRUCT_MEMBER(int32, renderer_id)
+  IPC_STRUCT_MEMBER(int32, render_view_id)
+  IPC_STRUCT_MEMBER(uint64, surface_id)
+  IPC_STRUCT_MEMBER(int32, route_id)
+  IPC_STRUCT_MEMBER(int, x)
+  IPC_STRUCT_MEMBER(int, y)
+  IPC_STRUCT_MEMBER(int, width)
+  IPC_STRUCT_MEMBER(int, height)
+#if defined(OS_MACOSX)
+  IPC_STRUCT_MEMBER(gfx::PluginWindowHandle, window)
+#endif
+IPC_STRUCT_END()
+
 IPC_STRUCT_BEGIN(GpuHostMsg_AcceleratedSurfaceRelease_Params)
   IPC_STRUCT_MEMBER(int32, renderer_id)
   IPC_STRUCT_MEMBER(int32, render_view_id)
@@ -151,9 +165,13 @@ IPC_MESSAGE_ROUTED2(AcceleratedSurfaceMsg_NewACK,
                     TransportDIB::Handle /* shared memory buffer */)
 
 // Tells the GPU process that the browser process handled the swap
-// buffers request with the given number.
+// buffers request.
 IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_BuffersSwappedACK)
 
+// Tells the GPU process that the browser process handled the
+// PostSubBuffer command.
+IPC_MESSAGE_ROUTED0(AcceleratedSurfaceMsg_PostSubBufferACK)
+
 // Tells the GPU process to remove all contexts.
 IPC_MESSAGE_CONTROL0(GpuMsg_Clean)
 
@@ -223,12 +241,16 @@ IPC_MESSAGE_CONTROL4(GpuHostMsg_ResizeView,
 IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfaceNew,
                      GpuHostMsg_AcceleratedSurfaceNew_Params)
 
-// This message notifies the browser process that the renderer
-// swapped the buffers associated with the given "window", which
-// should cause the browser to redraw the compositor's contents.
+// Same as above with a rect of the part of the surface that changed.
 IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfaceBuffersSwapped,
                      GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params)
 
+// This message notifies the browser process that the renderer
+// swapped a portion of the buffers associated with the given "window", which
+// should cause the browser to redraw the compositor's contents.
+IPC_MESSAGE_CONTROL1(GpuHostMsg_AcceleratedSurfacePostSubBuffer,
+                     GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params)
+
 // Tells the browser to release whatever resources are associated with
 // the given surface. The browser must send an ACK once this operation
 // is complete.
diff --git a/content/common/gpu/image_transport_surface.cc b/content/common/gpu/image_transport_surface.cc
index d0dfee1..94669cf 100644
--- a/content/common/gpu/image_transport_surface.cc
+++ b/content/common/gpu/image_transport_surface.cc
@@ -60,6 +60,8 @@ bool ImageTransportHelper::OnMessageReceived(const IPC::Message& message) {
   IPC_BEGIN_MESSAGE_MAP(ImageTransportHelper, message)
     IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_BuffersSwappedACK,
                         OnBuffersSwappedACK)
+    IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_PostSubBufferACK,
+                        OnPostSubBufferACK)
     IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_NewACK,
                         OnNewSurfaceACK)
     IPC_MESSAGE_HANDLER(AcceleratedSurfaceMsg_ResizeViewACK, OnResizeViewACK);
@@ -98,6 +100,17 @@ void ImageTransportHelper::SendAcceleratedSurfaceBuffersSwapped(
   manager_->Send(new GpuHostMsg_AcceleratedSurfaceBuffersSwapped(params));
 }
 
+void ImageTransportHelper::SendAcceleratedSurfacePostSubBuffer(
+    GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params params) {
+  params.renderer_id = renderer_id_;
+  params.render_view_id = render_view_id_;
+  params.route_id = route_id_;
+#if defined(OS_MACOSX)
+  params.window = handle_;
+#endif
+  manager_->Send(new GpuHostMsg_AcceleratedSurfacePostSubBuffer(params));
+}
+
 void ImageTransportHelper::SendResizeView(const gfx::Size& size) {
   manager_->Send(new GpuHostMsg_ResizeView(renderer_id_,
                                            render_view_id_,
@@ -124,6 +137,10 @@ void ImageTransportHelper::OnBuffersSwappedACK() {
   surface_->OnBuffersSwappedACK();
 }
 
+void ImageTransportHelper::OnPostSubBufferACK() {
+  surface_->OnPostSubBufferACK();
+}
+
 void ImageTransportHelper::OnNewSurfaceACK(
     uint64 surface_id,
     TransportDIB::Handle shm_handle) {
@@ -229,6 +246,11 @@ void PassThroughImageTransportSurface::OnNewSurfaceACK(
 }
 
 void PassThroughImageTransportSurface::OnBuffersSwappedACK() {
+  NOTREACHED();
+}
+
+void PassThroughImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
 }
 
 void PassThroughImageTransportSurface::OnResizeViewACK() {
diff --git a/content/common/gpu/image_transport_surface.h b/content/common/gpu/image_transport_surface.h
index b791c6e..b58ff12c 100644
--- a/content/common/gpu/image_transport_surface.h
+++ b/content/common/gpu/image_transport_surface.h
@@ -22,6 +22,7 @@ class GpuChannelManager;
 
 struct GpuHostMsg_AcceleratedSurfaceNew_Params;
 struct GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params;
+struct GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params;
 struct GpuHostMsg_AcceleratedSurfaceRelease_Params;
 
 namespace gfx {
@@ -57,6 +58,7 @@ class ImageTransportSurface {
   virtual void OnNewSurfaceACK(
       uint64 surface_id, TransportDIB::Handle surface_handle) = 0;
   virtual void OnBuffersSwappedACK() = 0;
+  virtual void OnPostSubBufferACK() = 0;
   virtual void OnResizeViewACK() = 0;
   virtual void OnResize(gfx::Size size) = 0;
 
@@ -94,6 +96,8 @@ class ImageTransportHelper : public IPC::Channel::Listener {
       GpuHostMsg_AcceleratedSurfaceNew_Params params);
   void SendAcceleratedSurfaceBuffersSwapped(
       GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params);
+  void SendAcceleratedSurfacePostSubBuffer(
+      GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params params);
   void SendAcceleratedSurfaceRelease(
       GpuHostMsg_AcceleratedSurfaceRelease_Params params);
   void SendResizeView(const gfx::Size& size);
@@ -113,6 +117,7 @@ class ImageTransportHelper : public IPC::Channel::Listener {
   // IPC::Message handlers.
   void OnNewSurfaceACK(uint64 surface_id, TransportDIB::Handle surface_handle);
   void OnBuffersSwappedACK();
+  void OnPostSubBufferACK();
   void OnResizeViewACK();
 
   // Backbuffer resize callback.
@@ -155,6 +160,7 @@ class PassThroughImageTransportSurface
   virtual void OnNewSurfaceACK(
       uint64 surface_id, TransportDIB::Handle surface_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
diff --git a/content/common/gpu/image_transport_surface_linux.cc b/content/common/gpu/image_transport_surface_linux.cc
index bcb1284..e106a9f 100644
--- a/content/common/gpu/image_transport_surface_linux.cc
+++ b/content/common/gpu/image_transport_surface_linux.cc
@@ -67,6 +67,8 @@ class EGLImageTransportSurface : public ImageTransportSurface,
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;
@@ -77,6 +79,7 @@ class EGLImageTransportSurface : public ImageTransportSurface,
   virtual void OnNewSurfaceACK(
       uint64 surface_id, TransportDIB::Handle surface_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
@@ -111,6 +114,7 @@ class GLXImageTransportSurface : public ImageTransportSurface,
   virtual bool Initialize() OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
   virtual void SetVisible(bool visible) OVERRIDE;
@@ -120,6 +124,7 @@ class GLXImageTransportSurface : public ImageTransportSurface,
   virtual void OnNewSurfaceACK(
       uint64 surface_id, TransportDIB::Handle surface_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
@@ -162,6 +167,8 @@ class OSMesaImageTransportSurface : public ImageTransportSurface,
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
 
  protected:
@@ -169,6 +176,7 @@ class OSMesaImageTransportSurface : public ImageTransportSurface,
   virtual void OnNewSurfaceACK(
       uint64 surface_id, TransportDIB::Handle surface_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
@@ -363,6 +371,16 @@ bool EGLImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool EGLImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
+std::string EGLImageTransportSurface::GetExtensions() {
+  return GLSurface::GetExtensions();
+}
+
 gfx::Size EGLImageTransportSurface::GetSize() {
   return back_surface_->size();
 }
@@ -377,6 +395,9 @@ void EGLImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void EGLImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
+}
 
 void EGLImageTransportSurface::OnResizeViewACK() {
   NOTREACHED();
@@ -513,6 +534,34 @@ bool GLXImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool GLXImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  gfx::NativeViewGLSurfaceGLX::PostSubBuffer(x, y, width, height);
+  glFlush();
+
+  if (needs_resize_) {
+    GpuHostMsg_AcceleratedSurfaceNew_Params params;
+    params.width = size_.width();
+    params.height = size_.height();
+    params.surface_id = window_;
+    helper_->SendAcceleratedSurfaceNew(params);
+    bound_ = true;
+    needs_resize_ = false;
+  }
+
+  GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params params;
+  params.surface_id = window_;
+  params.x = x;
+  params.y = y;
+  params.width = width;
+  params.height = height;
+
+  helper_->SendAcceleratedSurfacePostSubBuffer(params);
+
+  helper_->SetScheduled(false);
+  return true;
+}
+
 gfx::Size GLXImageTransportSurface::GetSize() {
   return size_;
 }
@@ -547,6 +596,10 @@ void GLXImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void GLXImageTransportSurface::OnPostSubBufferACK() {
+  helper_->SetScheduled(true);
+}
+
 void GLXImageTransportSurface::OnResizeViewACK() {
   NOTREACHED();
 }
@@ -648,10 +701,24 @@ bool OSMesaImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool OSMesaImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
+std::string OSMesaImageTransportSurface::GetExtensions() {
+  return GLSurface::GetExtensions();
+}
+
 void OSMesaImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void OSMesaImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
+}
+
 gfx::Size OSMesaImageTransportSurface::GetSize() {
   return size_;
 }
diff --git a/content/common/gpu/image_transport_surface_mac.cc b/content/common/gpu/image_transport_surface_mac.cc
index 8449f81..b7d9676 100644
--- a/content/common/gpu/image_transport_surface_mac.cc
+++ b/content/common/gpu/image_transport_surface_mac.cc
@@ -34,6 +34,8 @@ class IOSurfaceImageTransportSurface : public gfx::PbufferGLSurfaceCGL,
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;
@@ -43,6 +45,7 @@ class IOSurfaceImageTransportSurface : public gfx::PbufferGLSurfaceCGL,
   virtual void OnNewSurfaceACK(uint64 surface_id,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
@@ -86,6 +89,7 @@ class TransportDIBImageTransportSurface : public gfx::PbufferGLSurfaceCGL,
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;
@@ -93,6 +97,7 @@ class TransportDIBImageTransportSurface : public gfx::PbufferGLSurfaceCGL,
  protected:
   // ImageTransportSurface implementation
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnNewSurfaceACK(uint64 surface_id,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
@@ -226,6 +231,16 @@ bool IOSurfaceImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool IOSurfaceImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
+std::string IOSurfaceImageTransportSurface::GetExtensions() {
+  return gfx::GLSurface::GetExtensions();
+}
+
 gfx::Size IOSurfaceImageTransportSurface::GetSize() {
   return size_;
 }
@@ -234,6 +249,10 @@ void IOSurfaceImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void IOSurfaceImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
+}
+
 void IOSurfaceImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_id,
     TransportDIB::Handle /* shm_handle */) {
@@ -432,6 +451,10 @@ bool TransportDIBImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+std::string TransportDIBImageTransportSurface::GetExtensions() {
+  return gfx::GLSurface::GetExtensions();
+}
+
 gfx::Size TransportDIBImageTransportSurface::GetSize() {
   return size_;
 }
@@ -440,6 +463,10 @@ void TransportDIBImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void TransportDIBImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
+}
+
 void TransportDIBImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_id,
     TransportDIB::Handle shm_handle) {
diff --git a/content/common/gpu/image_transport_surface_win.cc b/content/common/gpu/image_transport_surface_win.cc
index 91040fe..f3eb9d5a 100644
--- a/content/common/gpu/image_transport_surface_win.cc
+++ b/content/common/gpu/image_transport_surface_win.cc
@@ -43,6 +43,7 @@ class PbufferImageTransportSurface
   virtual void OnNewSurfaceACK(uint64 surface_id,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
+  virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
@@ -121,14 +122,18 @@ void PbufferImageTransportSurface::OnBuffersSwappedACK() {
   helper_->SetScheduled(true);
 }
 
+void PbufferImageTransportSurface::OnPostSubBufferACK() {
+  NOTREACHED();
+}
+
 void PbufferImageTransportSurface::OnNewSurfaceACK(
     uint64 surface_id,
     TransportDIB::Handle shm_handle) {
-  NOTIMPLEMENTED();
+  NOTREACHED();
 }
 
 void PbufferImageTransportSurface::OnResizeViewACK() {
-  NOTIMPLEMENTED();
+  NOTREACHED();
 }
 
 void PbufferImageTransportSurface::OnResize(gfx::Size size) {
diff --git a/ui/gfx/gl/gl_surface.cc b/ui/gfx/gl/gl_surface.cc
index 9276d00..8329255 100644
--- a/ui/gfx/gl/gl_surface.cc
+++ b/ui/gfx/gl/gl_surface.cc
@@ -91,7 +91,9 @@ bool GLSurface::Resize(const gfx::Size& size) {
 }
 
 std::string GLSurface::GetExtensions() {
-  DCHECK_EQ(GetCurrent(), this);
+  // Use of GLSurfaceAdapter class means that we can't compare
+  // GetCurrent() and this directly.
+  DCHECK_EQ(GetCurrent()->GetHandle(), GetHandle());
   return std::string("");
 }
 
@@ -164,6 +166,14 @@ bool GLSurfaceAdapter::SwapBuffers() {
   return surface_->SwapBuffers();
 }
 
+bool GLSurfaceAdapter::PostSubBuffer(int x, int y, int width, int height) {
+  return surface_->PostSubBuffer(x, y, width, height);
+}
+
+std::string GLSurfaceAdapter::GetExtensions() {
+  return surface_->GetExtensions();
+}
+
 gfx::Size GLSurfaceAdapter::GetSize() {
   return surface_->GetSize();
 }
diff --git a/ui/gfx/gl/gl_surface.h b/ui/gfx/gl/gl_surface.h
index 8318368..e5b01b3 100644
--- a/ui/gfx/gl/gl_surface.h
+++ b/ui/gfx/gl/gl_surface.h
@@ -116,6 +116,8 @@ class GL_EXPORT GLSurfaceAdapter : public GLSurface {
   virtual bool Resize(const gfx::Size& size) OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual void* GetHandle() OVERRIDE;
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;