Prevent tracking metrics for cases such as 204s and downloads.

content/public/browser/navigation_handle.h

Index: content/public/browser/navigation_handle.h
diff --git a/content/public/browser/navigation_handle.h b/content/public/browser/navigation_handle.h
index 3c00e4a10afac5959e7ad7e89b67801980ffcf6d..e4c47cdc0c32d4f0074888a802a81d1d5542bee4 100644
--- a/content/public/browser/navigation_handle.h
+++ b/content/public/browser/navigation_handle.h
@@ -156,10 +156,9 @@ class CONTENT_EXPORT NavigationHandle {
   // GetNetErrorCode will be net::OK.
   virtual bool IsErrorPage() = 0;
 
-  // Returns the response headers for the request or nullptr if there are none.
-  // This should only be accessed after a redirect was encountered or after the
-  // navigation is ready to commit. The headers returned should not be modified,
-  // as modifications will not be reflected in the network stack.
+  // Returns the response headers for the request or nullptr if there are

[clamy, 2016/09/29 15:35:57]

Please mention that these are the final headers. we don't want people to be
confused and think they could get the headers from a redirect (wasn't a problem
before since you could only access them after the final response was received).

[Bryan McQuade, 2016/09/29 19:44:16]

Done, thanks!

+  // none. The headers returned should not be modified, as modifications will

[clamy, 2016/09/29 15:35:57]

nit: none or they have not been received yet.

[Bryan McQuade, 2016/09/29 19:44:16]

Done.

+  // not be reflected in the network stack.
   virtual const net::HttpResponseHeaders* GetResponseHeaders() = 0;
 
   // Resumes a navigation that was previously deferred by a NavigationThrottle.