cc: Remove unused metrics from RenderingStats.

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 76eae9515af5374870ee7b4e5378b8cd63cb836f..60e66e903d204ed37305bdf7be4b9f1dcda1c3a5 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -865,10 +865,6 @@ void ThreadProxy::BeginFrameOnMainThread(
     // to receive its callbacks before that.
     BlockingTaskRunner::CapturePostTasks blocked;
 
-    RenderingStatsInstrumentation* stats_instrumentation =
-        layer_tree_host_->rendering_stats_instrumentation();
-    base::TimeTicks start_time = stats_instrumentation->StartRecording();
-
     CompletionEvent completion;
     Proxy::ImplThreadTaskRunner()->PostTask(
         FROM_HERE,
@@ -879,8 +875,8 @@ void ThreadProxy::BeginFrameOnMainThread(
                    offscreen_context_provider));
     completion.Wait();
 
-    base::TimeDelta duration = stats_instrumentation->EndRecording(start_time);
-    stats_instrumentation->AddCommit(duration);
+    RenderingStatsInstrumentation* stats_instrumentation =
+        layer_tree_host_->rendering_stats_instrumentation();
     stats_instrumentation->IssueTraceEventForMainThreadStats();
     stats_instrumentation->AccumulateAndClearMainThreadStats();
   }