Make ExternalDataUseReporter independent of other data use classes

chrome/browser/android/data_usage/external_data_use_observer_bridge.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_BRIDGE_H_
 #define CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_BRIDGE_H_
 
 #include <jni.h>
 #include <stdint.h>
 
@@ skipping 57 matching lines @@
       const base::android::JavaParamRef<jobjectArray>& domain_path_regex,
       const base::android::JavaParamRef<jobjectArray>& label);
 
   // Reports data use to Java. Returns result asynchronously via
   // OnReportDataUseDone. ReportDataUse should not be called if a
   // request to submit data use is already in progress.
   void ReportDataUse(const std::string& label,
                      const std::string& tag,
                      net::NetworkChangeNotifier::ConnectionType connection_type,
                      const std::string& mcc_mnc,
-                     const base::Time& start_time,
-                     const base::Time& end_time,
+                     base::Time start_time,
+                     base::Time end_time,
                      int64_t bytes_downloaded,
                      int64_t bytes_uploaded) const;
 
   // Called by Java when the reporting of data usage has finished. |success|
   // is true if the request was successfully submitted to the external data
   // use observer by Java.
   void OnReportDataUseDone(JNIEnv* env,
                            const base::android::JavaParamRef<jobject>& obj,
                            bool success);
 
@@ skipping 35 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ExternalDataUseObserverBridge);
 };
 
 bool RegisterExternalDataUseObserver(JNIEnv* env);
 
 }  // namespace android
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_BRIDGE_H_