Notify WebContentsObservers of user interactions.

chrome/browser/engagement/site_engagement_helper.h

Index: chrome/browser/engagement/site_engagement_helper.h
diff --git a/chrome/browser/engagement/site_engagement_helper.h b/chrome/browser/engagement/site_engagement_helper.h
index c7f9e65206c2c8dd1790fa0e15dda265a945baed..9ba18079767d2f56a099f6eaf6c4a384dd671377 100644
--- a/chrome/browser/engagement/site_engagement_helper.h
+++ b/chrome/browser/engagement/site_engagement_helper.h
@@ -8,8 +8,6 @@
 #include "base/macros.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/engagement/site_engagement_metrics.h"
-#include "content/public/browser/render_view_host.h"
-#include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
@@ -35,79 +33,63 @@ class SiteEngagementHelper
   void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) override;
-  void RenderViewHostChanged(content::RenderViewHost* old_host,
-                             content::RenderViewHost* new_host) override;
   void WasShown() override;
   void WasHidden() override;
 
  private:
   // Class to encapsulate the user input listening.
   //
-  // Time on site is recorded by detecting any user input (mouse or keypress)
-  // per some discrete time unit. If there is user input, then record a positive
-  // site engagement.
+  // Time on site is recorded by detecting any user input (mouse click,
+  // keypress, or touch gesture tap) per some discrete time unit. If there is
+  // user input, then record a positive site engagement.
   //
   // When input is detected, SiteEngagementHelper::RecordUserInput is called,
   // and the input detection callbacks are paused for
   // g_seconds_between_user_input_check. This ensures that there is minimal
   // overhead in input listening, and that input over an extended length of time
   // is required to continually increase the engagement score.
-  class InputTracker {
+  class InputTracker : public content::WebContentsObserver {
    public:
-    explicit InputTracker(SiteEngagementHelper* helper);
-    ~InputTracker();
-
-    // Callback to handle key press events from the RenderViewHost.
-    bool HandleKeyPressEvent(const content::NativeWebKeyboardEvent& event);
-
-    // Callback to handle mouse events from the RenderViewHost.
-    bool HandleMouseEvent(const blink::WebMouseEvent& event);
+    explicit InputTracker(content::WebContents* web_contents,
+                          SiteEngagementHelper* helper);
+    ~InputTracker() override;
 
     // Begin tracking input after |initial_delay|.
-    void Start(content::RenderViewHost* host, base::TimeDelta initial_delay);
+    void Start(base::TimeDelta initial_delay);
 
     // Pause listening for user input, restarting listening after a delay.
     void Pause();
 
-    // Switches the InputTracker to another RenderViewHost, respecting the pause
-    // timer state.
-    void SwitchRenderViewHost(content::RenderViewHost* old_host,
-                              content::RenderViewHost* new_host);
-
     // Stop listening for user input.
     void Stop();
 
-    // Returns whether the InputTracker has been started for a RenderViewHost.
-    bool IsActive() const;
-
-    // Returns whether input tracking callbacks have been added to
-    // RenderViewHost.
+    // Returns whether the tracker will respond to user input via
+    // DidGetUserInteraction.
     bool is_tracking() const { return is_tracking_; }
 
-    content::RenderViewHost* host() const { return host_; }
-
     // Set the timer object for testing purposes.
     void SetPauseTimerForTesting(scoped_ptr<base::Timer> timer);
 
    private:
-    // Starts the timer for adding callbacks to the RenderViewHost.
+    friend class SiteEngagementHelperTest;
+
+    // Starts the timer for detecting user interaction.
     void StartTimer(base::TimeDelta delay);
 
-    // Adds/removes tracking callbacks to the RenderViewHost.
-    void AddCallbacks();
-    void RemoveCallbacks();
+    // Callback for StartTimer that activates the user input tracking.
+    void StartTracking();
+
+    // content::WebContentsObserver overrides.
+    void DidGetUserInteraction(const blink::WebInputEvent::Type type) override;
 
     SiteEngagementHelper* helper_;
     scoped_ptr<base::Timer> pause_timer_;
-    content::RenderViewHost* host_;
-    content::RenderWidgetHost::KeyPressEventCallback key_press_event_callback_;
-    content::RenderWidgetHost::MouseEventCallback mouse_event_callback_;
     bool is_tracking_;
   };
 
   explicit SiteEngagementHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<SiteEngagementHelper>;
-  friend class SiteEngagementServiceBrowserTest;
+  friend class SiteEngagementHelperTest;
 
   // Ask the SiteEngagementService to record engagement via user input at the
   // current contents location.