Add new latency_info for tracking browser composite time.

content/common/gpu/image_transport_surface.cc

Index: content/common/gpu/image_transport_surface.cc
diff --git a/content/common/gpu/image_transport_surface.cc b/content/common/gpu/image_transport_surface.cc
index 19b672b97845e0707bfb1824f3029662cd600c0e..16230bf933a8c10a86759a1068f128fedb4c0c9d 100644
--- a/content/common/gpu/image_transport_surface.cc
+++ b/content/common/gpu/image_transport_surface.cc
@@ -246,6 +246,10 @@ bool PassThroughImageTransportSurface::SwapBuffers() {
   // GetVsyncValues before SwapBuffers to work around Mali driver bug:
   // crbug.com/223558.
   SendVSyncUpdateIfAvailable();
+  for (size_t i = 0; i < latency_info_.size(); ++i) {
+    latency_info_[i].AddLatencyNumber(
+        ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT, 0, 0);
+  }
   bool result = gfx::GLSurfaceAdapter::SwapBuffers();
   for (size_t i = 0; i < latency_info_.size(); i++) {
     latency_info_[i].AddLatencyNumber(