Add User Actions and adding more details to UMA metrics for overscroll navigation

content/browser/web_contents/aura/overscroll_navigation_overlay.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "content/browser/web_contents/aura/overscroll_window_animation.h"
@@ skipping 14 matching lines @@
 // overscroll completes, this screenshot window is returned by
 // OnOverscrollComplete and |window_| is set to own it.
 // There are two overscroll cases, for the first one the main window is the web
 // contents window. At this stage, |window_| is null. The second case is
 // triggered if the user overscrolls after |window_| is set, before the page
 // finishes loading. When this happens, |window_| is the main window.
 class CONTENT_EXPORT OverscrollNavigationOverlay
     : public WebContentsObserver,
       public OverscrollWindowAnimation::Delegate {
  public:
-  // Note that this enum is used to back an UMA histogram, so it should be
-  // treated as append-only.
   enum NavigationDirection { NONE, FORWARD, BACK, NAVIGATION_COUNT };
 
   OverscrollNavigationOverlay(WebContentsImpl* web_contents,
                               aura::Window* web_contents_window);
 
   ~OverscrollNavigationOverlay() override;
 
   // Returns a pointer to the relay delegate we own.
   OverscrollControllerDelegate* relay_delegate() { return owa_.get(); }
 
  private:
   friend class OverscrollNavigationOverlayTest;
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, WithScreenshot);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, WithoutScreenshot);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, CannotNavigate);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, ForwardNavigation);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
+                           ForwardNavigationCancelled);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, CancelNavigation);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            CancelAfterSuccessfulNavigation);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, OverlayWindowSwap);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            CloseDuringAnimation);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            ImmediateLoadOnNavigate);
 
   // Resets state and starts observing |web_contents_| for page load/paint
@@ skipping 53 matching lines @@
 
   // The window that hosts the web contents.
   aura::Window* web_contents_window_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollNavigationOverlay);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_