Add metrics for triggering of JS dialogs on Android.

chrome/browser/android/tab_android.h

 // Copyright (c) 2012 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 CHROME_BROWSER_ANDROID_TAB_ANDROID_H_
 #define CHROME_BROWSER_ANDROID_TAB_ANDROID_H_
 
 #include <jni.h>
 #include <stdint.h>
 
@@ skipping 90 matching lines @@
 
   int GetAndroidId() const;
   int GetSyncId() const;
 
   // Return the tab title.
   base::string16 GetTitle() const;
 
   // Return the tab url.
   GURL GetURL() const;
 
+  // Return whether the tab is currently visible and the user can interact with
+  // it.
+  bool IsUserInteractable() const;
+
   // Load the tab if it was unloaded from memory.
   bool LoadIfNeeded();
 
   // Helper methods to make it easier to access objects from the associated
   // WebContents.  Can return NULL.
   Profile* GetProfile() const;
   sync_sessions::SyncedTabDelegate* GetSyncedTabDelegate() const;
 
   void SetWindowSessionID(SessionID::id_type window_id);
   void SetSyncId(int sync_id);
@@ skipping 146 matching lines @@
       web_contents_delegate_;
 
   std::unique_ptr<blimp::client::BlimpContents> blimp_contents_;
 
   std::unique_ptr<browser_sync::SyncedTabDelegateAndroid> synced_tab_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(TabAndroid);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_TAB_ANDROID_H_