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

content/renderer/render_widget.cc

 // Copyright (c) 2011 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 "content/renderer/render_widget.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 373 matching lines @@
   using_asynchronous_swapbuffers_ = false;
   // Schedule another frame so the compositor learns about it.
   scheduleComposite();
 }
 
 void RenderWidget::OnSwapBuffersComplete()
 {
   TRACE_EVENT0("renderer", "RenderWidget::OnSwapBuffersComplete");
   // When compositing deactivates, we reset the swapbuffers pending count.  The
   // swapbuffers acks may still arrive, however.
-  if (num_swapbuffers_complete_pending_ == 0) {
-    TRACE_EVENT0("renderer", "EarlyOut_ZeroSwapbuffersPending");
-    return;
+//if (num_swapbuffers_complete_pending_ == 0) {
+//  TRACE_EVENT0("renderer", "EarlyOut_ZeroSwapbuffersPending");
+//  return;
+//}
+//num_swapbuffers_complete_pending_--;

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

The num_swapbuffers_complete_pending_ count was wrong on OSX - perhaps when a
tab goes invisible. In any case, allowing it to EarlyOut here seemed to be
causing RAF-based demos to stop animating. Why not just render even when pending
is zero?

+  if (num_swapbuffers_complete_pending_ > 0) {
+    num_swapbuffers_complete_pending_--;
+  } else {
+    TRACE_EVENT0("renderer", "ZeroSwapbuffersPending");
   }
-  num_swapbuffers_complete_pending_--;
 
   // If update reply is still pending, then defer the update until that reply
   // occurs.
   if (update_reply_pending_){
     TRACE_EVENT0("renderer", "EarlyOut_UpdateReplyPending");
     return;
   }
 
   // If we are not accelerated rendering, then this is a stale swapbuffers from
   // when we were previously rendering.
@@ skipping 932 matching lines @@
 
 void RenderWidget::CleanupWindowInPluginMoves(gfx::PluginWindowHandle window) {
   for (WebPluginGeometryVector::iterator i = plugin_window_moves_.begin();
        i != plugin_window_moves_.end(); ++i) {
     if (i->window == window) {
       plugin_window_moves_.erase(i);
       break;
     }
   }
 }