Add an IPC method for Blink to call RapporService::RecordSample()

content/public/renderer/content_renderer_client.h

Index: content/public/renderer/content_renderer_client.h
diff --git a/content/public/renderer/content_renderer_client.h b/content/public/renderer/content_renderer_client.h
index ca4d51db881f8d8310f9e2fac5d4ce8c79d77974..64facecc10788890be0e653c1063f19b94fa7df9 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -291,6 +291,12 @@ class CONTENT_EXPORT ContentRendererClient {
   // Returns a user agent override specific for |url|, or empty string if
   // default user agent should be used.
   virtual std::string GetUserAgentOverrideForURL(const GURL& url);
+
+  // Record a sample string to a Rappor metric.
+  virtual void RecordRappor(const std::string& metric,
+                            const std::string& sample) {}
+  // Record a domain and registry of a url to a Rappor metric.
+  virtual void RecordRapporURL(const std::string& metric, const GURL& url) {}
 };
 
 }  // namespace content