Adding DRP specfic UMA for FirstContentfulPaint

content/browser/loader/navigation_resource_throttle.h

Index: content/browser/loader/navigation_resource_throttle.h
diff --git a/content/browser/loader/navigation_resource_throttle.h b/content/browser/loader/navigation_resource_throttle.h
index 6357b20aad4016e9c14d684c989ace9f04c1a09d..0908de5042e054057517b57fae5b07443fc416e2 100644
--- a/content/browser/loader/navigation_resource_throttle.h
+++ b/content/browser/loader/navigation_resource_throttle.h
@@ -8,38 +8,42 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "content/public/browser/navigation_throttle.h"
 #include "content/public/browser/resource_throttle.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
+class ResourceDispatcherHostImpl;
 
 // This ResourceThrottle is used to convey throttling information to the UI
 // thread during navigations. The UI thread can then use its NavigationThrottle
 // mechanism to interact with the navigation.
 class NavigationResourceThrottle : public ResourceThrottle {
  public:
-  NavigationResourceThrottle(net::URLRequest* request);
+  NavigationResourceThrottle(
+      net::URLRequest* request,
+      ResourceDispatcherHostImpl* resource_dispatcher_host);
   ~NavigationResourceThrottle() override;
 
   // ResourceThrottle overrides:
   void WillStartRequest(bool* defer) override;
   void WillRedirectRequest(const net::RedirectInfo& redirect_info,
                            bool* defer) override;
   void WillProcessResponse(bool* defer) override;
   const char* GetNameForLogging() const override;
 
  private:
   void OnUIChecksPerformed(NavigationThrottle::ThrottleCheckResult result);
 
   net::URLRequest* request_;
+  ResourceDispatcherHostImpl* resource_dispatcher_host_;

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

Is this guaranteed to be valid for the lifetime of the throttle?

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

RDH doesn't change and owns the ResourceLoader (via pending_loaders_), which
owns this. It will be valid here.

   base::WeakPtrFactory<NavigationResourceThrottle> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationResourceThrottle);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_NAVIGATION_RESOURCE_THROTTLE_H_