Revert of cc: Remove frame queuing from the scheduler.

cc/test/scheduler_test_common.h

Index: cc/test/scheduler_test_common.h
diff --git a/cc/test/scheduler_test_common.h b/cc/test/scheduler_test_common.h
index e8e34cd9ba42d6f40ad437cc0f88737049a34961..8bb8a9d565875f8e53dc4b7fba6042c7f01eb7db 100644
--- a/cc/test/scheduler_test_common.h
+++ b/cc/test/scheduler_test_common.h
@@ -129,6 +129,11 @@
       BeginFrameSource* begin_frame_source,
       std::unique_ptr<CompositorTimingHistory> compositor_timing_history);
 
+  // Extra test helper functionality
+  bool IsBeginRetroFrameArgsEmpty() const {
+    return begin_retro_frame_args_.empty();
+  }
+
   bool SwapThrottled() const { return state_machine_.SwapThrottled(); }
 
   bool NeedsBeginMainFrame() const {
@@ -143,10 +148,6 @@
 
   bool begin_frames_expected() const {
     return begin_frame_source_ && observing_begin_frame_source_;
-  }
-
-  int current_frame_number() const {
-    return state_machine_.current_frame_number();
   }
 
   ~TestScheduler() override;