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..a48d91e85779330d9d359c34ddc139f4465f407f 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -570,8 +570,11 @@ 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 a RAPPOR privacy-preserving metric, see: https://www.chromium.org/developers/design-documents/rappor.
+    // recordRappor records a sample string, while recordRapporURL records the domain and registry of a url.
     virtual void recordRappor(const char* metric, const WebString& sample) { }
+    virtual void recordRapporURL(const char* metric, const blink::WebURL& url) { }
 
     // GPU ----------------------------------------------------------------
     //