Create and integrate a metrics service client into Blimp engine.

blimp/engine/session/blimp_engine_session.h

Index: blimp/engine/session/blimp_engine_session.h
diff --git a/blimp/engine/session/blimp_engine_session.h b/blimp/engine/session/blimp_engine_session.h
index a78bb664c4b7a560cf1ca9a07c75f8b76be33b11..e5decfc834c8347136f8445042a90cbba21b0b06 100644
--- a/blimp/engine/session/blimp_engine_session.h
+++ b/blimp/engine/session/blimp_engine_session.h
@@ -84,6 +84,8 @@ class BlimpEngineSession
   // values for e.g. screen size pending real values being supplied by the
   // client.
   void Initialize();
+  // Finalizes the metrics reporting client.

[Wez, 2016/04/26 01:38:19]

nit: Blank line before this comment, plz, to match the style of other comments
in this code.

[Jess, 2016/04/26 21:24:11]

Done.

+  void Finalize();
 
   BlimpBrowserContext* browser_context() { return browser_context_.get(); }