Unified BeginFrame scheduling

content/browser/renderer_host/display_link_mac.h

Index: content/browser/renderer_host/display_link_mac.h
diff --git a/content/browser/renderer_host/display_link_mac.h b/content/browser/renderer_host/display_link_mac.h
index 1833f8f2d3fee60474bb9bb9e4655aaeb9d09169..555875422c9216da97dfd88537b6c23c9379e8f2 100644
--- a/content/browser/renderer_host/display_link_mac.h
+++ b/content/browser/renderer_host/display_link_mac.h
@@ -11,6 +11,7 @@
 #include "base/lazy_instance.h"
 #include "base/mac/scoped_typeref.h"
 #include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
@@ -19,6 +20,12 @@ namespace content {
 
 class DisplayLinkMac : public base::RefCounted<DisplayLinkMac> {
  public:
+  class Observer {
+   public:
+    virtual void OnVSync(base::TimeTicks timebase,
+                         base::TimeDelta interval) = 0;
+  };
+
   static scoped_refptr<DisplayLinkMac> GetForDisplay(
       CGDirectDisplayID display_id);
 
@@ -27,6 +34,9 @@ class DisplayLinkMac : public base::RefCounted<DisplayLinkMac> {
       base::TimeTicks* timebase,
       base::TimeDelta* interval);
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  private:
   friend class base::RefCounted<DisplayLinkMac>;
 
@@ -65,6 +75,8 @@ class DisplayLinkMac : public base::RefCounted<DisplayLinkMac> {
   // Lock for sharing data between UI thread and display-link thread.
   base::Lock lock_;
 
+  ObserverList<Observer> observer_list_;
+
   // Each display link instance consumes a non-negligible number of cycles, so
   // make all display links on the same screen share the same object.
   typedef std::map<CGDirectDisplayID, DisplayLinkMac*> DisplayMap;