Adding UMA stats for Blimp Client

blimp/client/core/compositor/blimp_compositor.cc

Index: blimp/client/core/compositor/blimp_compositor.cc
diff --git a/blimp/client/core/compositor/blimp_compositor.cc b/blimp/client/core/compositor/blimp_compositor.cc
index d6031c83fba11ff639dabbdf869755185c651888..370047a6e03c73a85aca3bf0b77e3e04a6074f5e 100644
--- a/blimp/client/core/compositor/blimp_compositor.cc
+++ b/blimp/client/core/compositor/blimp_compositor.cc
@@ -7,6 +7,7 @@
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
@@ -132,6 +133,9 @@ void BlimpCompositor::OnCompositorMessageReceived(
     case cc::proto::CompositorMessageToImpl::UNKNOWN:
       NOTIMPLEMENTED() << "Ignoring message of UNKNOWN type";
       break;
+    case cc::proto::CompositorMessageToImpl::START_COMMIT:
+      UMA_HISTOGRAM_MEMORY_KB("Blimp.Compositor.CommitSizeKb",
+                              (float)message->ByteSize() / 1024);
     default:
       // We should have a receiver if we're getting compositor messages that
       // are not INITIALIZE_IMPL or CLOSE_IMPL.