Mac Overlays: Add GPU back-pressure

ui/accelerated_widget_mac/display_link_mac.cc

 // Copyright 2014 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/accelerated_widget_mac/display_link_mac.h"
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/trace_event/trace_event.h"
 
 namespace base {
 
 template<>
 struct ScopedTypeRefTraits<CVDisplayLinkRef> {
   static void Retain(CVDisplayLinkRef object) {
     CVDisplayLinkRetain(object);
   }
   static void Release(CVDisplayLinkRef object) {
     CVDisplayLinkRelease(object);
   }
 };
 
 }  // namespace base
 
 namespace ui {
 
 // static
 scoped_refptr<DisplayLinkMac> DisplayLinkMac::GetForDisplay(
     CGDirectDisplayID display_id) {
+  if (!display_id)
+    return NULL;

[tapted, 2015/08/06 00:56:49]

nit: nullptr

[ccameron, 2015/08/06 01:42:47]

Done.

+
   // Return the existing display link for this display, if it exists.
   DisplayMap::iterator found = display_map_.Get().find(display_id);
   if (found != display_map_.Get().end()) {
     return found->second;
   }
 
   CVReturn ret = kCVReturnSuccess;
 
   base::ScopedTypeRef<CVDisplayLinkRef> display_link;
   ret = CVDisplayLinkCreateWithCGDisplay(
@@ skipping 135 matching lines @@
   DisplayLinkMac* display_link_mac = found->second;
   display_link_mac->timebase_and_interval_valid_ = false;
 }
 
 // static
 base::LazyInstance<DisplayLinkMac::DisplayMap>
     DisplayLinkMac::display_map_ = LAZY_INSTANCE_INITIALIZER;
 
 }  // ui