[Page Load Metrics] Add mojom file to page load metrics.

chrome/renderer/page_load_metrics/metrics_render_frame_observer.h

Index: chrome/renderer/page_load_metrics/metrics_render_frame_observer.h
diff --git a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.h b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.h
index 3b9ad1e915cf3a676e7ba8a0557378eea7038a91..70ad64d417a1f1eac5f147741961aeea6a72a829 100644
--- a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.h
+++ b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.h
@@ -48,7 +48,7 @@ class MetricsRenderFrameObserver : public content::RenderFrameObserver {
 
   void SendMetrics();
   virtual bool ShouldSendMetrics() const;
-  virtual PageLoadTiming GetTiming() const;
+  virtual mojo::StructPtr<mojom::PageLoadTiming> GetTiming() const;

[Ken Rockot(use gerrit already), 2017/05/15 17:26:34]

nit: please use mojom::PageLoadTimingPtr instead of
mojo::StructPtr<mojom::PageLoadTiming>, here and anywhere else you explicitly
name mojo::StructPtr<Foo>

[Bryan McQuade, 2017/05/15 17:38:24]

FWIW, I worry a little bit about using PageLoadTimingPtr here. My assumption at
first when reading those types was that they were bare pointer types.
mojo::StructPtr<> OTOH makes it clearer that this is a templated pointer
management class of some kind. My pref would be to use mojo::StructPtr<> if it's
ok, as most of the people using this codebase aren't deeply familiar with mojo,
but if there's a reason it's problematic I'm fine with switching to
PageLoadTimingPtr.

[lpy, 2017/05/15 22:40:18]

Done.

   virtual std::unique_ptr<base::Timer> CreateTimer() const;
   virtual bool HasNoRenderFrame() const;
   virtual bool IsMainFrame() const;