Add histograms for data usage

chrome/browser/android/data_usage/external_data_use_observer.h

 // Copyright 2015 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_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_
 #define CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 64 matching lines @@
 
   // Returns the pointer to the DataUseTabModel object owned by |this|. The
   // caller does not owns the returned pointer.
   DataUseTabModel* GetDataUseTabModel() const;
 
   // Called by ExternalDataUseObserverBridge::OnReportDataUseDone when a data
   // use report has been submitted. |success| is true if the request was
   // successfully submitted to the external data use observer by Java.
   void OnReportDataUseDone(bool success);
 
+  // Called by ExternalDataUseObserverBridge when matching rules are fetched
+  // from the Java object.
+  void OnFetchMatchingRulesDone() const;
+
   // Called by DataUseMatcher. |should_register| is true if |this| should
   // register as a data use observer.
   void ShouldRegisterAsDataUseObserver(bool should_register);
 
   // Fetches the matching rules asynchronously.
   void FetchMatchingRules();
 
   base::WeakPtr<ExternalDataUseObserver> GetWeakPtr();
 
  private:
@@ skipping 183 matching lines @@
   base::WeakPtrFactory<ExternalDataUseObserver> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalDataUseObserver);
 };
 
 }  // namespace android
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_