Add SurfaceWillDraw notification

cc/test/fake_surface_observer.cc

Index: cc/test/fake_surface_observer.cc
diff --git a/cc/test/fake_surface_observer.cc b/cc/test/fake_surface_observer.cc
index 0a44e5f8caa46a110de0e93f4a015d46e15f7f58..d5bb3ed7bd6c1318e55ff2a92960ba99362e949e 100644
--- a/cc/test/fake_surface_observer.cc
+++ b/cc/test/fake_surface_observer.cc
@@ -14,6 +14,7 @@ FakeSurfaceObserver::~FakeSurfaceObserver() {}
 void FakeSurfaceObserver::Reset() {
   last_ack_ = BeginFrameAck();
   damaged_surfaces_.clear();
+  will_draw_surfaces_.clear();
   last_surface_info_ = SurfaceInfo();
   last_created_surface_id_ = SurfaceId();
 }
@@ -22,6 +23,11 @@ bool FakeSurfaceObserver::IsSurfaceDamaged(const SurfaceId& surface_id) const {
   return damaged_surfaces_.count(surface_id) > 0;
 }
 
+bool FakeSurfaceObserver::SurfaceWillDrawCalled(
+    const SurfaceId& surface_id) const {
+  return will_draw_surfaces_.count(surface_id) > 0;
+}
+
 bool FakeSurfaceObserver::OnSurfaceDamaged(const SurfaceId& surface_id,
                                            const BeginFrameAck& ack) {
   if (ack.has_damage)
@@ -30,6 +36,10 @@ bool FakeSurfaceObserver::OnSurfaceDamaged(const SurfaceId& surface_id,
   return ack.has_damage && damage_display_;
 }
 
+void FakeSurfaceObserver::OnSurfaceWillDraw(const SurfaceId& surface_id) {
+  will_draw_surfaces_.insert(surface_id);
+}
+
 void FakeSurfaceObserver::OnSurfaceCreated(const SurfaceInfo& surface_info) {
   last_created_surface_id_ = surface_info.id();
   last_surface_info_ = surface_info;