make BeginFrameSourceMixIn's SetNeedsBeginFrame final

cc/scheduler/begin_frame_source.cc

Index: cc/scheduler/begin_frame_source.cc
diff --git a/cc/scheduler/begin_frame_source.cc b/cc/scheduler/begin_frame_source.cc
index 8ef3b6798bbbb7cd04d76b48ce4da3c2635bb4c4..c44ea1a5667a499d216faee4b2ef98d85c8de344 100644
--- a/cc/scheduler/begin_frame_source.cc
+++ b/cc/scheduler/begin_frame_source.cc
@@ -414,11 +414,10 @@ bool BeginFrameSourceMultiplexer::NeedsBeginFrames() const {
   }
 }
 
-void BeginFrameSourceMultiplexer::SetNeedsBeginFrames(bool needs_begin_frames) {
-  DEBUG_FRAMES("BeginFrameSourceMultiplexer::SetNeedsBeginFrames",
-               "active_source",
-               active_source_,
-               "needs_begin_frames",
+void BeginFrameSourceMultiplexer::OnNeedsBeginFramesChange(
+    bool needs_begin_frames) {
+  DEBUG_FRAMES("BeginFrameSourceMultiplexer::OnNeedsBeginFramesChange",
+               "active_source", active_source_, "needs_begin_frames",
                needs_begin_frames);
   if (active_source_) {
     active_source_->SetNeedsBeginFrames(needs_begin_frames);