media: Add Rappor reporting in MediaLog

media/base/media_log.h

Index: media/base/media_log.h
diff --git a/media/base/media_log.h b/media/base/media_log.h
index d08e5426ad6ae5912cb98de6d329a40f76902640..64a3f3d4c86578fe5ade5070f883edeb27f7b955 100644
--- a/media/base/media_log.h
+++ b/media/base/media_log.h
@@ -47,6 +47,11 @@ class MEDIA_EXPORT MediaLog : public base::RefCountedThreadSafe<MediaLog> {
   // Retrieve an error message, if any.
   virtual std::string GetLastErrorMessage();
 
+  // Records the domain and registry of the current frame security origin to a
+  // Rappor privacy-preserving metric. See:
+  //   https://www.chromium.org/developers/design-documents/rappor
+  virtual void RecordRapporWithSecurityOrigin(const std::string& metric);

[xhwang, 2016/06/15 00:19:07]

Reporting security origin is consistent with our existing rappor metrics. We can
also report the WebMediaPlayerSource URL, but I am not sure how useful that will
be.

[DaleCurtis, 2016/06/15 00:33:47]

I think this is better for now, as the player url is often a cdn redirect which
may not be useful in tracking down the main page.

+
   // Helper methods to create events and their parameters.
   std::unique_ptr<MediaLogEvent> CreateEvent(MediaLogEvent::Type type);
   std::unique_ptr<MediaLogEvent> CreateBooleanEvent(MediaLogEvent::Type type,