Decouple BrowserCompositorOutputSurface from BeginFrameSource.

components/exo/wayland/server.cc

Index: components/exo/wayland/server.cc
diff --git a/components/exo/wayland/server.cc b/components/exo/wayland/server.cc
index 7b3d47ed80040647c1ddc52cbfadf1d94d6f513a..fd1f75682ee6bd32c3d79d733f9a2662446dac15 100644
--- a/components/exo/wayland/server.cc
+++ b/components/exo/wayland/server.cc
@@ -1860,7 +1860,7 @@ void bind_remote_shell(wl_client* client,
 
 // Implements VSync timing interface by monitoring a compositor for updates
 // to VSync parameters.
-class VSyncTiming : public ui::CompositorVSyncManager::Observer {
+class VSyncTiming : public cc::VSyncObserver {
  public:
   ~VSyncTiming() { vsync_manager_->RemoveObserver(this); }
 
@@ -1873,7 +1873,7 @@ class VSyncTiming : public ui::CompositorVSyncManager::Observer {
     return vsync_timing;
   }
 
-  // Overridden from ui::CompositorVSyncManager::Observer:
+  // Overridden from cc::VSyncObserver:
   void OnUpdateVSyncParameters(base::TimeTicks timebase,
                                base::TimeDelta interval) override {
     uint64_t timebase_us = timebase.ToInternalValue();