Fix the mac hangup when force-compositing-mode is enabled

chrome/browser/renderer_host/render_widget_host_view_mac.mm

Index: chrome/browser/renderer_host/render_widget_host_view_mac.mm
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 bf4ce950865f2af8515c63ac99c92a43520098c6..439bd8a04dabb94795ab3632fd5fe6d2037aec67 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
@@ -574,6 +574,7 @@ void RenderWidgetHostViewMac::RenderViewGone(base::TerminationStatus status,
 }
 
 void RenderWidgetHostViewMac::Destroy() {
+  TRACE_EVENT0("browser", "RenderWidgetHostViewMac::Destroy");
   // On Windows, popups are implemented with a popup window style, so that when
   // an event comes in that would "cancel" it, it receives the OnCancelMode
   // message and can kill itself. Alas, on the Mac, views cannot capture events
@@ -703,6 +704,9 @@ RenderWidgetHostViewMac::AllocateFakePluginWindowHandle(bool opaque,
   // Create an NSView to host the plugin's/compositor's pixels.
   gfx::PluginWindowHandle handle =
       plugin_container_manager_.AllocateFakePluginWindowHandle(opaque, root);
+  TRACE_EVENT1("browser",
+               "RenderWidgetHostViewMac::AllocateFakePluginWindowHandle",
+               "window", handle);
 
   scoped_nsobject<AcceleratedPluginView> plugin_view(
       [[AcceleratedPluginView alloc] initWithRenderWidgetHostViewMac:this
@@ -718,6 +722,9 @@ RenderWidgetHostViewMac::AllocateFakePluginWindowHandle(bool opaque,
 void RenderWidgetHostViewMac::DestroyFakePluginWindowHandle(
     gfx::PluginWindowHandle window) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  TRACE_EVENT1("browser",
+               "RenderWidgetHostViewMac::DestroyFakePluginWindowHandle",
+               "window", window);
   PluginViewMap::iterator it = plugin_views_.find(window);
   DCHECK(plugin_views_.end() != it);
   if (plugin_views_.end() == it) {
@@ -734,6 +741,9 @@ void RenderWidgetHostViewMac::DestroyFakePluginWindowHandle(
 // This is called by AcceleratedPluginView's -dealloc.
 void RenderWidgetHostViewMac::DeallocFakePluginWindowHandle(
     gfx::PluginWindowHandle window) {
+  TRACE_EVENT1("browser",
+               "RenderWidgetHostViewMac::DeallocFakePluginWindowHandle",
+               "window", window);
   // When a browser window with a GpuScheduler is closed, the render process
   // will attempt to finish all GL commands. It will busy-wait on the GPU
   // process until the command queue is empty. If a paint is pending, the GPU
@@ -759,7 +769,6 @@ void RenderWidgetHostViewMac::DeallocFakePluginWindowHandle(
 AcceleratedPluginView* RenderWidgetHostViewMac::ViewForPluginWindowHandle(
     gfx::PluginWindowHandle window) {
   PluginViewMap::iterator it = plugin_views_.find(window);
-  DCHECK(plugin_views_.end() != it);
   if (plugin_views_.end() == it)
     return nil;
   return it->second;
@@ -810,13 +819,20 @@ void RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped(
     int32 route_id,
     int gpu_host_id,
     uint64 swap_buffers_count) {
-  TRACE_EVENT0("browser",
-      "RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped");
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   AcceleratedPluginView* view = ViewForPluginWindowHandle(window);
-  DCHECK(view);
-  if (!view)
+  TRACE_EVENT1("browser",
+      "RenderWidgetHostViewMac::AcceleratedSurfaceBuffersSwapped",
+      "view", view);
+  if (!view) {
+    // This happens, and we can't let the GPU go without an ack.
+    // TODO: Why does this happen? Does it matter?

[jbates, 2011/06/07 16:47:52]

Looks like this may be a recent ToT bug. It does not seem to happen in the
latest m13 branch.

+    AcknowledgeSwapBuffers(renderer_id,
+                           route_id,
+                           gpu_host_id,
+                           swap_buffers_count);
     return;
+  }
 
   plugin_container_manager_.SetSurfaceWasPaintedTo(window, surface_id);
 
@@ -863,7 +879,7 @@ void RenderWidgetHostViewMac::AcknowledgeSwapBuffers(
     int32 route_id,
     int gpu_host_id,
     uint64 swap_buffers_count) {
-  TRACE_EVENT1("gpu", "RenderWidgetHostViewMac::AcknowledgeSwapBuffers",
+  TRACE_EVENT1("browser", "RenderWidgetHostViewMac::AcknowledgeSwapBuffers",
       "swap_buffers_count", swap_buffers_count);
   // Called on the display link thread. Hand actual work off to the IO thread,
   // because |GpuProcessHost::Get()| can only be called there.