[page_load_metrics] Get navigation_start from NavigationHandle

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 3b2bbadda772a2f31a97b5faff489b0b730728c9..8097b06ee15d837ecc795ad17803b411588e0857 100644
--- a/content/public/browser/navigation_handle.h
+++ b/content/public/browser/navigation_handle.h
@@ -39,6 +39,10 @@ class CONTENT_EXPORT NavigationHandle {
   // The WebContents the navigation is taking place in.
   WebContents* GetWebContents();
 
+  // The time the navigation started, recorded either in the renderer or in the
+  // browser process. Corresponds to Navigation Timing API.
+  virtual const base::TimeTicks& navigation_start() = 0;

[clamy, 2015/11/17 12:52:31]

This should be called NavigationStart instead of navigation_start.

[Charlie Harrison, 2015/11/17 14:47:32]

Ah, okay. In that case I'll need to change it in the impl as well. Nasko wanted
it hacker_case, but I guess now that it's virtual it shouldn't be.

+
   // Parameters available at network request start time ------------------------
   //
   // The following parameters are only available when the network request is