When accelerated compositing is enabled, we create a plugin-like pair of windows,

CompositorHostWindow and CompositorWindow inside the RenderWidgetHostView. The host-side
HWND is used to position the compositor output relative to plugins; the GPU process creates the
compositor window as a child of the CompositorHostWindow.

Once we land webkit bugfix 49396, ANGLE issue 3038042, Chromium issue 4671003, this will fix
bugs 54301 and 61516 for windows.


BUG=none
TEST=none

Review URL: http://codereview.chromium.org/4815001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@67495 0039d316-1c4b-4281-b951-d872f2087c98

15 files changed, 294 insertions, 33 deletions

diff --git a/chrome/browser/gpu_process_host.cc b/chrome/browser/gpu_process_host.cc
index afa904c..c321f97 100644
--- a/chrome/browser/gpu_process_host.cc
+++ b/chrome/browser/gpu_process_host.cc
@@ -177,6 +177,9 @@ void GpuProcessHost::OnControlMessageReceived(const IPC::Message& message) {
                         OnAcceleratedSurfaceSetIOSurface)
     IPC_MESSAGE_HANDLER(GpuHostMsg_AcceleratedSurfaceBuffersSwapped,
                         OnAcceleratedSurfaceBuffersSwapped)
+#elif defined(OS_WIN)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(GpuHostMsg_CreateCompositorHostWindow,
+                                    OnCreateCompositorHostWindow)
 #endif
     // If the IO thread does not handle the message then automatically route it
     // to the UI thread. The UI thread will report an error if it does not
@@ -305,8 +308,8 @@ namespace {
 class BuffersSwappedDispatcher : public Task {
  public:
   BuffersSwappedDispatcher(
-      int32 renderer_id,
-      int32 render_view_id,
+      int renderer_id,
+      int render_view_id,
       gfx::PluginWindowHandle window,
       uint64 surface_id,
       int32 route_id,
@@ -338,8 +341,8 @@ class BuffersSwappedDispatcher : public Task {
   }
 
  private:
-  int32 renderer_id_;
-  int32 render_view_id_;
+  int renderer_id_;
+  int render_view_id_;
   gfx::PluginWindowHandle window_;
   uint64 surface_id_;
   int32 route_id_;
@@ -366,6 +369,47 @@ void GpuProcessHost::OnAcceleratedSurfaceBuffersSwapped(
           params.route_id,
           params.swap_buffers_count));
 }
+
+#elif defined(OS_WIN)
+
+namespace {
+
+void SendDelayedReply(IPC::Message* reply_msg) {
+  GpuProcessHost::Get()->Send(reply_msg);
+}
+
+void CreateCompositorHostWindowDispatcher(
+    int renderer_id,
+    int render_view_id,
+    IPC::Message* reply_msg) {
+  RenderViewHost* host = RenderViewHost::FromID(renderer_id,
+                                                render_view_id);
+  if (!host) {
+    return;
+  }
+
+  RenderWidgetHostView* view = host->view();
+  gfx::PluginWindowHandle id = view->CreateCompositorHostWindow();
+
+
+  GpuHostMsg_CreateCompositorHostWindow::WriteReplyParams(reply_msg, id);
+  BrowserThread::PostTask(
+    BrowserThread::IO, FROM_HERE,
+    NewRunnableFunction(&SendDelayedReply, reply_msg));
+}
+
+}  // namespace
+
+void GpuProcessHost::OnCreateCompositorHostWindow(
+    int renderer_id,
+    int render_view_id,
+    IPC::Message* reply_message) {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      NewRunnableFunction(&CreateCompositorHostWindowDispatcher,
+          renderer_id, render_view_id, reply_message));
+}
+
 #endif
 
 void GpuProcessHost::SendEstablishChannelReply(
diff --git a/chrome/browser/gpu_process_host.h b/chrome/browser/gpu_process_host.h
index 4b40a25..8219355 100644
--- a/chrome/browser/gpu_process_host.h
+++ b/chrome/browser/gpu_process_host.h
@@ -93,6 +93,10 @@ class GpuProcessHost : public BrowserChildProcessHost, public NonThreadSafe {
       const GpuHostMsg_AcceleratedSurfaceSetIOSurface_Params& params);
   void OnAcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params);
+#elif defined(OS_WIN)
+  void OnCreateCompositorHostWindow(int renderer_id,
+                                    int render_view_id,
+                                    IPC::Message* reply_message);
 #endif
 
   // Sends the response for establish channel request to the renderer.
diff --git a/chrome/browser/gpu_process_host_ui_shim.cc b/chrome/browser/gpu_process_host_ui_shim.cc
index 2e3a531..d8257a8 100644
--- a/chrome/browser/gpu_process_host_ui_shim.cc
+++ b/chrome/browser/gpu_process_host_ui_shim.cc
@@ -6,6 +6,7 @@
 
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/gpu_process_host.h"
+#include "chrome/browser/renderer_host/render_view_host.h"
 #include "chrome/common/child_process_logging.h"
 #include "chrome/common/gpu_messages.h"
 
@@ -105,6 +106,15 @@ void GpuProcessHostUIShim::OnGraphicsInfoCollected(const GPUInfo& gpu_info) {
   child_process_logging::SetGpuInfo(gpu_info);
 }
 
+void GpuProcessHostUIShim::OnScheduleComposite(int renderer_id,
+    int render_view_id) {
+  RenderViewHost* host = RenderViewHost::FromID(renderer_id,
+                                                render_view_id);
+  if (!host) {
+    return;
+  }
+  host->ScheduleComposite();
+}
 void GpuProcessHostUIShim::OnControlMessageReceived(
     const IPC::Message& message) {
   DCHECK(CalledOnValidThread());
@@ -112,6 +122,10 @@ void GpuProcessHostUIShim::OnControlMessageReceived(
   IPC_BEGIN_MESSAGE_MAP(GpuProcessHostUIShim, message)
     IPC_MESSAGE_HANDLER(GpuHostMsg_GraphicsInfoCollected,
                         OnGraphicsInfoCollected)
+#if defined(OS_WIN)
+    IPC_MESSAGE_HANDLER(GpuHostMsg_ScheduleComposite,
+                        OnScheduleComposite);
+#endif
     IPC_MESSAGE_UNHANDLED_ERROR()
   IPC_END_MESSAGE_MAP()
 }
diff --git a/chrome/browser/gpu_process_host_ui_shim.h b/chrome/browser/gpu_process_host_ui_shim.h
index d77c783..eda33d2 100644
--- a/chrome/browser/gpu_process_host_ui_shim.h
+++ b/chrome/browser/gpu_process_host_ui_shim.h
@@ -62,7 +62,7 @@ class GpuProcessHostUIShim : public IPC::Channel::Sender,
 
   // Message handlers.
   void OnGraphicsInfoCollected(const GPUInfo& gpu_info);
-
+  void OnScheduleComposite(int32 renderer_id, int32 render_view_id);
   void OnControlMessageReceived(const IPC::Message& message);
 
   int last_routing_id_;
diff --git a/chrome/browser/renderer_host/render_widget_host.cc b/chrome/browser/renderer_host/render_widget_host.cc
index 4482bbd..caf7d14 100644
--- a/chrome/browser/renderer_host/render_widget_host.cc
+++ b/chrome/browser/renderer_host/render_widget_host.cc
@@ -77,7 +77,7 @@ RenderWidgetHost::RenderWidgetHost(RenderProcessHost* process,
       routing_id_(routing_id),
       is_loading_(false),
       is_hidden_(false),
-      is_gpu_rendering_active_(false),
+      is_accelerated_compositing_active_(false),
       repaint_ack_pending_(false),
       resize_ack_pending_(false),
       mouse_move_pending_(false),
@@ -157,8 +157,8 @@ void RenderWidgetHost::OnMessageReceived(const IPC::Message &msg) {
                         OnMsgImeUpdateTextInputState)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ImeCancelComposition,
                         OnMsgImeCancelComposition)
-    IPC_MESSAGE_HANDLER(ViewHostMsg_GpuRenderingActivated,
-                        OnMsgGpuRenderingActivated)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_DidActivateAcceleratedCompositing,
+                        OnMsgDidActivateAcceleratedCompositing)
 #if defined(OS_MACOSX)
     IPC_MESSAGE_HANDLER(ViewHostMsg_GetScreenInfo, OnMsgGetScreenInfo)
     IPC_MESSAGE_HANDLER(ViewHostMsg_GetWindowRect, OnMsgGetWindowRect)
@@ -232,7 +232,7 @@ void RenderWidgetHost::WasRestored() {
   // the backing store exists.
   bool needs_repainting;
   if (needs_repainting_on_restore_ || !backing_store ||
-      is_gpu_rendering_active()) {
+      is_accelerated_compositing_active()) {
     needs_repainting = true;
     needs_repainting_on_restore_ = false;
   } else {
@@ -402,8 +402,9 @@ void RenderWidgetHost::DonePaintingToBackingStore() {
 }
 
 void RenderWidgetHost::ScheduleComposite() {
-  DCHECK(!is_hidden_ || !is_gpu_rendering_active_) <<
-      "ScheduleCompositeAndSync called while hidden!";
+  if (is_hidden_ || !is_accelerated_compositing_active_) {
+      return;
+  }
 
   // Send out a request to the renderer to paint the view if required.
   if (!repaint_ack_pending_ && !resize_ack_pending_ && !view_being_painted_) {
@@ -658,7 +659,7 @@ void RenderWidgetHost::RendererExited() {
   current_size_.SetSize(0, 0);
   current_reserved_rect_.SetRect(0, 0, 0, 0);
   is_hidden_ = false;
-  is_gpu_rendering_active_ = false;
+  is_accelerated_compositing_active_ = false;
 
   if (view_) {
     view_->RenderViewGone();
@@ -832,7 +833,7 @@ void RenderWidgetHost::OnMsgUpdateRect(
   DCHECK(!params.bitmap_rect.IsEmpty());
   DCHECK(!params.view_size.IsEmpty());
 
-  if (!is_gpu_rendering_active_) {
+  if (!is_accelerated_compositing_active_) {
     const size_t size = params.bitmap_rect.height() *
         params.bitmap_rect.width() * 4;
     TransportDIB* dib = process_->GetTransportDIB(params.bitmap);
@@ -879,7 +880,7 @@ void RenderWidgetHost::OnMsgUpdateRect(
     // which attempts to move the plugin windows and in the process could
     // dispatch other window messages which could cause the view to be
     // destroyed.
-    if (view_ && !is_gpu_rendering_active_) {
+    if (view_ && !is_accelerated_compositing_active_) {
       view_being_painted_ = true;
       view_->DidUpdateBackingStore(params.scroll_rect, params.dx, params.dy,
                                    params.copy_rects);
@@ -977,14 +978,16 @@ void RenderWidgetHost::OnMsgImeCancelComposition() {
     view_->ImeCancelComposition();
 }
 
-void RenderWidgetHost::OnMsgGpuRenderingActivated(bool activated) {
+void RenderWidgetHost::OnMsgDidActivateAcceleratedCompositing(bool activated) {
 #if defined(OS_MACOSX)
-  bool old_state = is_gpu_rendering_active_;
+  bool old_state = is_accelerated_compositing_active_;
 #endif
-  is_gpu_rendering_active_ = activated;
+  is_accelerated_compositing_active_ = activated;
 #if defined(OS_MACOSX)
-  if (old_state != is_gpu_rendering_active_ && view_)
+  if (old_state != is_accelerated_compositing_active_ && view_)
     view_->GpuRenderingStateDidChange();
+#elif defined(OS_WIN)
+  view_->ShowCompositorHostWindow(is_accelerated_compositing_active_);
 #elif defined(TOOLKIT_USES_GTK)
   view_->AcceleratedCompositingActivated(activated);
 #endif
@@ -1089,7 +1092,6 @@ void RenderWidgetHost::OnMsgDestroyPluginContainer(gfx::PluginWindowHandle id) {
     NOTIMPLEMENTED();
   }
 }
-
 #endif
 
 void RenderWidgetHost::PaintBackingStoreRect(
diff --git a/chrome/browser/renderer_host/render_widget_host.h b/chrome/browser/renderer_host/render_widget_host.h
index 9f2225b..47e4dab 100644
--- a/chrome/browser/renderer_host/render_widget_host.h
+++ b/chrome/browser/renderer_host/render_widget_host.h
@@ -203,7 +203,9 @@ class RenderWidgetHost : public IPC::Channel::Listener,
   virtual void LostCapture();
 
   // Tells us whether the page is rendered directly via the GPU process.
-  bool is_gpu_rendering_active() { return is_gpu_rendering_active_; }
+  bool is_accelerated_compositing_active() {
+    return is_accelerated_compositing_active_;
+  }
 
   // Notifies the RenderWidgetHost that the View was destroyed.
   void ViewDestroyed();
@@ -484,7 +486,7 @@ class RenderWidgetHost : public IPC::Channel::Listener,
                                     const gfx::Rect& caret_rect);
   void OnMsgImeCancelComposition();
 
-  void OnMsgGpuRenderingActivated(bool activated);
+  void OnMsgDidActivateAcceleratedCompositing(bool activated);
 
 #if defined(OS_MACOSX)
   void OnMsgGetScreenInfo(gfx::NativeViewId view,
@@ -564,7 +566,7 @@ class RenderWidgetHost : public IPC::Channel::Listener,
   bool is_hidden_;
 
   // True when a page is rendered directly via the GPU process.
-  bool is_gpu_rendering_active_;
+  bool is_accelerated_compositing_active_;
 
   // Set if we are waiting for a repaint ack for the view.
   bool repaint_ack_pending_;
diff --git a/chrome/browser/renderer_host/render_widget_host_view.h b/chrome/browser/renderer_host/render_widget_host_view.h
index 4ad2c41..8235ebf 100644
--- a/chrome/browser/renderer_host/render_widget_host_view.h
+++ b/chrome/browser/renderer_host/render_widget_host_view.h
@@ -246,6 +246,12 @@ class RenderWidgetHostView {
   virtual void AcceleratedCompositingActivated(bool activated) = 0;
 #endif
 
+#if defined(OS_WIN)
+  virtual gfx::PluginWindowHandle CreateCompositorHostWindow() = 0;
+  virtual void WillWmDestroy() = 0;
+  virtual void ShowCompositorHostWindow(bool show) = 0;
+#endif
+
   // Toggles visual muting of the render view area. This is on when a
   // constrained window is showing.
   virtual void SetVisuallyDeemphasized(bool deemphasized) = 0;
diff --git a/chrome/browser/renderer_host/render_widget_host_view_gtk.cc b/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
index bf39966..aa43529 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_gtk.cc
@@ -814,7 +814,7 @@ void RenderWidgetHostViewGtk::Paint(const gfx::Rect& damage_rect) {
   // If the GPU process is rendering directly into the View,
   // call the compositor directly.
   RenderWidgetHost* render_widget_host = GetRenderWidgetHost();
-  if (render_widget_host->is_gpu_rendering_active()) {
+  if (render_widget_host->is_accelerated_compositing_active()) {
     host_->ScheduleComposite();
     return;
   }
diff --git a/chrome/browser/renderer_host/render_widget_host_view_mac.mm b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
index 307eb2e..b0ef7e6 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
@@ -745,7 +745,7 @@ void RenderWidgetHostViewMac::DidUpdateBackingStore(
   if (!is_hidden_) {
     std::vector<gfx::Rect> rects(copy_rects);
 
-    // Because the findbar might be open, we cannot use scrollRect:by: here.  For
+    // Because the findbar might be open, we cannot use scrollRect:by: here. For
     // now, simply mark all of scroll rect as dirty.
     if (!scroll_rect.IsEmpty())
       rects.push_back(scroll_rect);
@@ -1019,8 +1019,8 @@ void RenderWidgetHostViewMac::UpdateRootGpuViewVisibility(
   // Plugins are destroyed on page navigate. The compositor layer on the other
   // hand is created on demand and then stays alive until its renderer process
   // dies (usually on cross-domain navigation). Instead, only a flag
-  // |is_gpu_rendering_active()| is flipped when the compositor output should be
-  // shown/hidden.
+  // |is_accelerated_compositing_active()| is flipped when the compositor output
+  // should be shown/hidden.
   // Show/hide the view belonging to the compositor here.
   plugin_container_manager_.set_gpu_rendering_active(show_gpu_widget);
 
@@ -1085,9 +1085,9 @@ void RenderWidgetHostViewMac::AcknowledgeSwapBuffers(
 
 void RenderWidgetHostViewMac::GpuRenderingStateDidChange() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (GetRenderWidgetHost()->is_gpu_rendering_active()) {
+  if (GetRenderWidgetHost()->is_accelerated_compositing_active()) {
     UpdateRootGpuViewVisibility(
-        GetRenderWidgetHost()->is_gpu_rendering_active());
+        GetRenderWidgetHost()->is_accelerated_compositing_active());
   } else {
     needs_gpu_visibility_update_after_repaint_ = true;
   }
@@ -1685,7 +1685,8 @@ void RenderWidgetHostViewMac::SetTextInputActive(bool active) {
 
   const gfx::Rect damagedRect([self flipNSRectToRect:dirtyRect]);
 
-  if (renderWidgetHostView_->render_widget_host_->is_gpu_rendering_active()) {
+  if (renderWidgetHostView_->render_widget_host_->
+      is_accelerated_compositing_active()) {
     gfx::Rect gpuRect;
 
     gfx::PluginWindowHandle root_handle =
diff --git a/chrome/browser/renderer_host/render_widget_host_view_views.cc b/chrome/browser/renderer_host/render_widget_host_view_views.cc
index 20797ad..b9f386e 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_views.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_views.cc
@@ -350,7 +350,7 @@ void RenderWidgetHostViewViews::Paint(gfx::Canvas* canvas) {
   // Don't do any painting if the GPU process is rendering directly
   // into the View.
   RenderWidgetHost* render_widget_host = GetRenderWidgetHost();
-  if (render_widget_host->is_gpu_rendering_active()) {
+  if (render_widget_host->is_accelerated_compositing_active()) {
     return;
   }
 
@@ -603,7 +603,8 @@ bool RenderWidgetHostViewViews::ContainsNativeView(
   return false;
 }
 
-void RenderWidgetHostViewViews::AcceleratedCompositingActivated(bool activated) {
+void RenderWidgetHostViewViews::AcceleratedCompositingActivated(
+    bool activated) {
   // TODO(anicolao): figure out if we need something here
   if (activated)
     NOTIMPLEMENTED();
diff --git a/chrome/browser/renderer_host/render_widget_host_view_win.cc b/chrome/browser/renderer_host/render_widget_host_view_win.cc
index 3f9b9b1..df78d00 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_win.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_win.cc
@@ -281,6 +281,7 @@ RenderWidgetHostView* RenderWidgetHostView::CreateViewForWidget(
 
 RenderWidgetHostViewWin::RenderWidgetHostViewWin(RenderWidgetHost* widget)
     : render_widget_host_(widget),
+      compositor_host_window_(NULL),
       track_mouse_leave_(false),
       ime_notification_(false),
       capture_enter_key_(false),
@@ -382,6 +383,13 @@ void RenderWidgetHostViewWin::SetSize(const gfx::Size& size) {
   UINT swp_flags = SWP_NOSENDCHANGING | SWP_NOOWNERZORDER | SWP_NOCOPYBITS |
       SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE | SWP_DEFERERASE;
   SetWindowPos(NULL, 0, 0, size.width(), size.height(), swp_flags);
+  if (compositor_host_window_) {
+    ::SetWindowPos(compositor_host_window_,
+        NULL,
+        0, 0,
+        size.width(), size.height(),
+        SWP_NOSENDCHANGING | SWP_NOCOPYBITS | SWP_NOZORDER | SWP_NOACTIVATE);
+  }
   render_widget_host_->WasResized();
   EnsureTooltip();
 }
@@ -709,6 +717,26 @@ void RenderWidgetHostViewWin::RenderViewGone() {
   DestroyWindow();
 }
 
+static BOOL CALLBACK AddChildWindowToVector(HWND hwnd, LPARAM lparam) {
+  std::vector<HWND>* vector = reinterpret_cast<std::vector<HWND>*>(lparam);
+  vector->push_back(hwnd);
+  return TRUE;
+}
+
+void RenderWidgetHostViewWin::WillWmDestroy() {
+  if (!compositor_host_window_)
+    return;
+
+  std::vector<HWND> all_child_windows;
+  ::EnumChildWindows(compositor_host_window_, AddChildWindowToVector,
+      reinterpret_cast<LPARAM>(&all_child_windows));
+  if (all_child_windows.size()) {
+    DCHECK(all_child_windows.size() == 1);
+    ::ShowWindow(all_child_windows[0], SW_HIDE);
+    ::SetParent(all_child_windows[0], NULL);
+  }
+}
+
 void RenderWidgetHostViewWin::WillDestroyRenderWidget(RenderWidgetHost* rwh) {
   if (rwh == render_widget_host_)
     render_widget_host_ = NULL;
@@ -722,6 +750,7 @@ void RenderWidgetHostViewWin::Destroy() {
   // OnFinalMessage();
   close_on_deactivate_ = false;
   being_destroyed_ = true;
+  WillWmDestroy();
   DestroyWindow();
 }
 
@@ -849,7 +878,7 @@ void RenderWidgetHostViewWin::OnPaint(HDC unused_dc) {
   // If the GPU process is rendering directly into the View,
   // call the compositor directly.
   RenderWidgetHost* render_widget_host = GetRenderWidgetHost();
-  if (render_widget_host->is_gpu_rendering_active()) {
+  if (render_widget_host->is_accelerated_compositing_active()) {
     // We initialize paint_dc here so that BeginPaint()/EndPaint()
     // get called to validate the region.
     CPaintDC paint_dc(m_hWnd);
@@ -1457,6 +1486,136 @@ void RenderWidgetHostViewWin::Observe(NotificationType type,
   browser_accessibility_manager_.reset(NULL);
 }
 
+// Looks through the children windows of the CompositorHostWindow. If the
+// compositor child window is found, its size is checked against the host
+// window's size. If the child is smaller in either dimensions, we fill
+// the host window with white to avoid unseemly cracks.
+static void PaintCompositorHostWindow(HWND hWnd) {
+  PAINTSTRUCT paint;
+  BeginPaint(hWnd, &paint);
+
+  std::vector<HWND> child_windows;
+  EnumChildWindows(hWnd, AddChildWindowToVector,
+      reinterpret_cast<LPARAM>(&child_windows));
+
+  if (child_windows.size()) {
+    HWND child = child_windows[0];
+
+    RECT host_rect, child_rect;
+    GetClientRect(hWnd, &host_rect);
+    if (GetClientRect(child, &child_rect)) {
+      if (child_rect.right < host_rect.right ||
+         child_rect.bottom != host_rect.bottom) {
+          FillRect(paint.hdc, &host_rect,
+              static_cast<HBRUSH>(GetStockObject(WHITE_BRUSH)));
+      }
+    }
+  }
+  EndPaint(hWnd, &paint);
+}
+
+// WndProc for the compositor host window. We use this instead of Default so
+// we can drop WM_PAINT and WM_ERASEBKGD messages on the floor.
+static LRESULT CALLBACK CompositorHostWindowProc(HWND hWnd, UINT message,
+                                                 WPARAM wParam, LPARAM lParam) {
+  switch (message) {
+  case WM_ERASEBKGND:
+    return 0;
+  case WM_DESTROY:
+    return 0;
+  case WM_PAINT:
+    PaintCompositorHostWindow(hWnd);
+    return 0;
+  default:
+    return DefWindowProc(hWnd, message, wParam, lParam);
+  }
+}
+
+// Creates a HWND within the RenderWidgetHostView that will serve as a host
+// for a HWND that the GPU process will create. The host window is used
+// to Z-position the GPU's window relative to other plugin windows.
+gfx::PluginWindowHandle RenderWidgetHostViewWin::CreateCompositorHostWindow() {
+  DCHECK(!compositor_host_window_);
+  static ATOM window_class = 0;
+  if (!window_class) {
+    WNDCLASSEX wcex;
+    wcex.cbSize         = sizeof(WNDCLASSEX);
+    wcex.style          = 0;
+    wcex.lpfnWndProc    = CompositorHostWindowProc;
+    wcex.cbClsExtra     = 0;
+    wcex.cbWndExtra     = 0;
+    wcex.hInstance      = GetModuleHandle(NULL);
+    wcex.hIcon          = 0;
+    wcex.hCursor        = 0;
+    wcex.hbrBackground  = NULL;
+    wcex.lpszMenuName   = 0;
+    wcex.lpszClassName  = L"CompositorHostWindowClass";
+    wcex.hIconSm        = 0;
+    window_class = RegisterClassEx(&wcex);
+    DCHECK(window_class);
+  }
+
+  compositor_host_window_ = CreateWindowEx(
+    WS_EX_LEFT | WS_EX_LTRREADING | WS_EX_RIGHTSCROLLBAR,
+    MAKEINTATOM(window_class), 0,
+    WS_CHILD | WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_DISABLED,
+    0, 0, 0, 0, m_hWnd, 0, GetModuleHandle(NULL), 0);
+  DCHECK(compositor_host_window_);
+
+  // We need to not just "WM_SHOW" the new indow, but reparent it
+  // below any existing plugin existing windows.
+  ShowCompositorHostWindow(true);
+
+  return static_cast<gfx::PluginWindowHandle>(compositor_host_window_);
+}
+
+void RenderWidgetHostViewWin::ShowCompositorHostWindow(bool show) {
+  // When we first create the compositor, we will get a show request from
+  // the renderer before we have gotten the create request from the GPU. In this
+  // case, simply ignore the show request.
+  if (compositor_host_window_ == NULL)
+    return;
+
+  if (show) {
+    UINT flags = SWP_NOSENDCHANGING | SWP_NOCOPYBITS | SWP_NOZORDER |
+      SWP_NOACTIVATE | SWP_DEFERERASE | SWP_SHOWWINDOW;
+    gfx::Rect rect = GetViewBounds();
+    ::SetWindowPos(compositor_host_window_, NULL, 0, 0,
+        rect.width(), rect.height(),
+        flags);
+
+    // Get all the child windows of this view, including the compositor window.
+    std::vector<HWND> all_child_windows;
+    ::EnumChildWindows(m_hWnd, AddChildWindowToVector,
+        reinterpret_cast<LPARAM>(&all_child_windows));
+
+    // Build a list of just the plugin window handles
+    std::vector<HWND> plugin_windows;
+    bool compositor_host_window_found = false;
+    for (size_t i = 0; i < all_child_windows.size(); ++i) {
+      if (all_child_windows[i] != compositor_host_window_)
+        plugin_windows.push_back(all_child_windows[i]);
+      else
+        compositor_host_window_found = true;
+    }
+    DCHECK(compositor_host_window_found);
+
+    // Set all the plugin windows to be "after" the compositor window.
+    // When the compositor window is created, gets placed above plugins.
+    for (size_t i = 0; i < plugin_windows.size(); ++i) {
+      HWND next;
+      if (i + 1 < plugin_windows.size())
+        next = plugin_windows[i+1];
+      else
+        next = compositor_host_window_;
+      ::SetWindowPos(plugin_windows[i], next, 0, 0, 0, 0,
+          SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
+    }
+  } else {
+    ::ShowWindow(compositor_host_window_, SW_HIDE);
+  }
+}
+
 void RenderWidgetHostViewWin::SetAccessibilityFocus(int acc_obj_id) {
   if (!browser_accessibility_manager_.get() ||
       !render_widget_host_ ||
diff --git a/chrome/browser/renderer_host/render_widget_host_view_win.h b/chrome/browser/renderer_host/render_widget_host_view_win.h
index 13609e6..7f0a30e 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_win.h
+++ b/chrome/browser/renderer_host/render_widget_host_view_win.h
@@ -154,6 +154,7 @@ class RenderWidgetHostViewWin
       const gfx::Rect& scroll_rect, int scroll_dx, int scroll_dy,
       const std::vector<gfx::Rect>& copy_rects);
   virtual void RenderViewGone();
+  virtual void WillWmDestroy();  // called by TabContents before DestroyWindow
   virtual void WillDestroyRenderWidget(RenderWidgetHost* rwh);
   virtual void Destroy();
   virtual void SetTooltipText(const std::wstring& tooltip_text);
@@ -161,6 +162,10 @@ class RenderWidgetHostViewWin
   virtual void SetBackground(const SkBitmap& background);
   virtual bool ContainsNativeView(gfx::NativeView native_view) const;
   virtual void SetVisuallyDeemphasized(bool deemphasized);
+
+  virtual gfx::PluginWindowHandle CreateCompositorHostWindow();
+  virtual void ShowCompositorHostWindow(bool show);
+
   virtual void OnAccessibilityNotifications(
       const std::vector<ViewHostMsg_AccessibilityNotification_Params>& params);
 
@@ -265,6 +270,9 @@ class RenderWidgetHostViewWin
   // The associated Model.
   RenderWidgetHost* render_widget_host_;
 
+  // When we are doing accelerated compositing
+  HWND compositor_host_window_;
+
   // The cursor for the page. This is passed up from the renderer.
   WebCursor current_cursor_;
 
diff --git a/chrome/browser/renderer_host/test/test_render_view_host.cc b/chrome/browser/renderer_host/test/test_render_view_host.cc
index 65d82e9..e4dc729 100644
--- a/chrome/browser/renderer_host/test/test_render_view_host.cc
+++ b/chrome/browser/renderer_host/test/test_render_view_host.cc
@@ -181,6 +181,17 @@ void TestRenderWidgetHostView::AcceleratedSurfaceBuffersSwapped(
 
 void TestRenderWidgetHostView::GpuRenderingStateDidChange() {
 }
+#elif defined(OS_WIN)
+gfx::PluginWindowHandle TestRenderWidgetHostView::CreateCompositorHostWindow(
+  ) {
+    return gfx::kNullPluginWindow;
+}
+
+void TestRenderWidgetHostView::WillWmDestroy() {
+}
+
+void TestRenderWidgetHostView::ShowCompositorHostWindow(bool show) {
+}
 #endif
 
 TestRenderViewHostFactory::TestRenderViewHostFactory(
diff --git a/chrome/browser/renderer_host/test/test_render_view_host.h b/chrome/browser/renderer_host/test/test_render_view_host.h
index fe6daa7..4f5d355 100644
--- a/chrome/browser/renderer_host/test/test_render_view_host.h
+++ b/chrome/browser/renderer_host/test/test_render_view_host.h
@@ -124,6 +124,10 @@ class TestRenderWidgetHostView : public RenderWidgetHostView {
       int32 route_id,
       uint64 swap_buffers_count);
   virtual void GpuRenderingStateDidChange();
+#elif defined(OS_WIN)
+  virtual gfx::PluginWindowHandle CreateCompositorHostWindow();
+  virtual void WillWmDestroy();
+  virtual void ShowCompositorHostWindow(bool show);
 #endif
   virtual void SetVisuallyDeemphasized(bool deemphasized) { }
 
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index c846d62..4a225b2 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -486,8 +486,13 @@ TabContents::~TabContents() {
 #if defined(OS_WIN)
   // If we still have a window handle, destroy it. GetNativeView can return
   // NULL if this contents was part of a window that closed.
-  if (GetNativeView())
+  if (GetNativeView()) {
+    RenderViewHost* host = render_view_host();
+    if (host && host->view()) {
+      host->view()->WillWmDestroy();
+    }
     ::DestroyWindow(GetNativeView());
+  }
 #endif
 
   // OnCloseStarted isn't called in unit tests.