Adding DRP specfic UMA for FirstContentfulPaint

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h

Index: chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
index 3b580561e71451187a3602b0430359bcbef16e11..8c5b1dcc654992e148c9d059439d1bad0341af6c 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
@@ -19,20 +19,24 @@ class DelayedResourceQueue;
 class DownloadRequestLimiter;
 
 namespace extensions {
 class UserScriptListener;
 }
 
 namespace safe_browsing {
 class SafeBrowsingService;
 }
 
+namespace content {
+class NavigationData;
+}
+
 // Implements ResourceDispatcherHostDelegate. Currently used by the Prerender
 // system to abort requests and add to the load flags when a request begins.
 class ChromeResourceDispatcherHostDelegate
     : public content::ResourceDispatcherHostDelegate {
  public:
   ChromeResourceDispatcherHostDelegate();
   ~ChromeResourceDispatcherHostDelegate() override;
 
   // ResourceDispatcherHostDelegate implementation.
   bool ShouldBeginRequest(const std::string& method,
@@ -79,20 +83,22 @@ class ChromeResourceDispatcherHostDelegate
                          content::ResourceResponse* response,
                          IPC::Sender* sender) override;
   void OnRequestRedirected(const GURL& redirect_url,
                            net::URLRequest* request,
                            content::ResourceContext* resource_context,
                            content::ResourceResponse* response) override;
   void RequestComplete(net::URLRequest* url_request) override;
   bool ShouldEnableLoFiMode(
       const net::URLRequest& url_request,
       content::ResourceContext* resource_context) override;
+  std::unique_ptr<content::NavigationData> GetNavigationData(
+      net::URLRequest* request) const override;
 
   // Called on the UI thread. Allows switching out the
   // ExternalProtocolHandler::Delegate for testing code.
   static void SetExternalProtocolHandlerDelegateForTesting(
       ExternalProtocolHandler::Delegate* delegate);
 
  private:
 #if defined(ENABLE_EXTENSIONS)
   struct StreamTargetInfo {
     std::string extension_id;