NOT READY FOR REVIEW - switch to a subscriber model for rendering stats

cc/layer_tree_host.cc

Index: cc/layer_tree_host.cc
diff --git a/cc/layer_tree_host.cc b/cc/layer_tree_host.cc
index 06085b1ea745483cd1dd5b342140a2ad06ef4075..42c5a0eaf390a6ac81f4ac9f7dc8a617cb3d3c34 100644
--- a/cc/layer_tree_host.cc
+++ b/cc/layer_tree_host.cc
@@ -4,6 +4,7 @@
 
 #include "config.h"
 
+#include "cc/rendering_stats_subscriber.h"
 #include "cc/layer_tree_host.h"
 
 #include "Region.h"
@@ -760,6 +761,19 @@ void LayerTreeHost::stopRateLimiter(WebKit::WebGraphicsContext3D* context)
     }
 }
 
+void LayerTreeHost::startRecordingRenderingStats()
+{
+    m_renderingStatsSubscriber = RenderingStatsSubscriber::create();
+    m_proxy->startRecordingRenderingStats();
+}
+
+void LayerTreeHost::stopRecordingRenderingStats(RenderingStats* stats)
+{
+    // TODO(vollick): populate the stats here.
+    m_renderingStatsSubscriber.reset();
+    m_proxy->stopRecordingRenderingStats(stats);
+}
+
 void LayerTreeHost::rateLimit()
 {
     // Force a no-op command on the compositor context, so that any ratelimiting commands will wait for the compositing