Add RAPPOR metric recording for Device{Orientation,Motion} in blink.

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index ba29cdc917c98a608e47829834f868a84e89741f..d4e39b86105a28966651e4d58b0249bc1d40feff 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -570,8 +570,12 @@ public:
     virtual void histogramEnumeration(const char* name, int sample, int boundaryValue) { }
     // Unlike enumeration histograms, sparse histograms only allocate memory for non-empty buckets.
     virtual void histogramSparse(const char* name, int sample) { }
-    // Record to RAPPOR.
+
+    // Record to RAPPOR, see: https://www.chromium.org/developers/design-documents/rappor
+    // Records a sample string to a Rappor privacy-preserving metric.
     virtual void recordRappor(const char* metric, const WebString& sample) { }
+    // Records a domain and registry of a url to a Rappor privacy-preserving metric.

[Mike West, 2015/04/14 05:20:38]

Nit: These method-level comments seem somewhat self-explanatory from the method
signature. I'd suggest dropping them. Adding the URL to the top-level comment is
a good idea, though!

[timvolodine, 2015/04/14 10:24:22]

I've added these comments on suggestion of koji@ and asvitkine@, I think one of
the concerns was that recordRapporURL might give the wrong impression that we
are logging urls..

+    virtual void recordRapporURL(const char* metric, const blink::WebURL& url) { }
 
     // GPU ----------------------------------------------------------------
     //