[cc] Plumb BeginFrameAcks through SurfaceManager to DisplayScheduler.

cc/surfaces/display_scheduler_unittest.cc

Index: cc/surfaces/display_scheduler_unittest.cc
diff --git a/cc/surfaces/display_scheduler_unittest.cc b/cc/surfaces/display_scheduler_unittest.cc
index a03aeacb66196a17b4d8342551d207599cca0f62..98ad32f0b974831d8ea82872d06f6ac7e08c7e9e 100644
--- a/cc/surfaces/display_scheduler_unittest.cc
+++ b/cc/surfaces/display_scheduler_unittest.cc
@@ -32,12 +32,18 @@ class FakeDisplaySchedulerClient : public DisplaySchedulerClient {
     return true;
   }
 
+  const SurfaceAggregator::SurfaceIndexMap& GetPreviousContainedSurfaces()
+      override {
+    return previous_contained_surfaces_;
+  }
+
   void Reset() { draw_and_swap_count_ = 0; }
 
   int draw_and_swap_count() const { return draw_and_swap_count_; }
 
  protected:
   int draw_and_swap_count_;
+  SurfaceAggregator::SurfaceIndexMap previous_contained_surfaces_;
 };
 
 class TestDisplayScheduler : public DisplayScheduler {