cc: fix another data race in RenderingStatsInstrumentation.

cc/debug/rendering_stats_instrumentation.cc

Index: cc/debug/rendering_stats_instrumentation.cc
diff --git a/cc/debug/rendering_stats_instrumentation.cc b/cc/debug/rendering_stats_instrumentation.cc
index 5dbc113073e7b8b45c90d591c9bb51d679656f22..d58ae80eb92cba3b744b63a76bcf2b1fb0ed8a3c 100644
--- a/cc/debug/rendering_stats_instrumentation.cc
+++ b/cc/debug/rendering_stats_instrumentation.cc
@@ -18,6 +18,18 @@ RenderingStatsInstrumentation::RenderingStatsInstrumentation()
 
 RenderingStatsInstrumentation::~RenderingStatsInstrumentation() {}
 
+MainThreadRenderingStats
+RenderingStatsInstrumentation::main_thread_rendering_stats() {
+  base::AutoLock scoped_lock(lock_);
+  return main_stats_;
+}
+
+ImplThreadRenderingStats
+RenderingStatsInstrumentation::impl_thread_rendering_stats() {
+  base::AutoLock scoped_lock(lock_);
+  return impl_stats_;
+}
+
 RenderingStats RenderingStatsInstrumentation::GetRenderingStats() {
   base::AutoLock scoped_lock(lock_);
   RenderingStats rendering_stats;