Adding DRP specfic UMA for FirstContentfulPaint

content/browser/loader/navigation_url_loader_delegate.h

Index: content/browser/loader/navigation_url_loader_delegate.h
diff --git a/content/browser/loader/navigation_url_loader_delegate.h b/content/browser/loader/navigation_url_loader_delegate.h
index 201fa86297e4de6fc08000e304fd9c8296f931a1..4ffdd9558e0d52dfd6096243f82244754965922b 100644
--- a/content/browser/loader/navigation_url_loader_delegate.h
+++ b/content/browser/loader/navigation_url_loader_delegate.h
@@ -10,38 +10,40 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
 
 namespace net {
 struct RedirectInfo;
 }
 
 namespace content {
 
+class NavigationData;
 class StreamHandle;
 struct ResourceResponse;
 
 // PlzNavigate: The delegate interface to NavigationURLLoader.
 class CONTENT_EXPORT NavigationURLLoaderDelegate {
  public:
   // Called when the request is redirected. Call FollowRedirect to continue
   // processing the request.
   virtual void OnRequestRedirected(
       const net::RedirectInfo& redirect_info,
       const scoped_refptr<ResourceResponse>& response) = 0;
 
   // Called when the request receives its response. No further calls will be
   // made to the delegate. The response body is returned as a stream in
   // |body_stream|.

[bengr, 2016/04/29 21:14:23]

Also describe navigation_data

[RyanSturm, 2016/05/02 19:52:22]

Done.

   virtual void OnResponseStarted(
       const scoped_refptr<ResourceResponse>& response,
-      std::unique_ptr<StreamHandle> body_stream) = 0;
+      std::unique_ptr<StreamHandle> body_stream,
+      std::unique_ptr<NavigationData> navigation_data) = 0;
 
   // Called if the request fails before receving a response. |net_error| is a
   // network error code for the failure. |has_stale_copy_in_cache| is true if
   // there is a stale copy of the unreachable page in cache.
   virtual void OnRequestFailed(bool has_stale_copy_in_cache, int net_error) = 0;
 
   // Called after the network request has begun on the IO thread at time
   // |timestamp|. This is just a thread hop but is used to compare timing
   // against the pre-PlzNavigate codepath which didn't start the network request
   // until after the renderer was initialized.