Make ExternalDataUseReporter independent of other data use classes

chrome/browser/android/data_usage/external_data_use_observer_bridge.cc

 // 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.
 
 #include "chrome/browser/android/data_usage/external_data_use_observer_bridge.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/android/context_utils.h"
@@ skipping 117 matching lines @@
 
   data_use_tab_model_->RegisterURLRegexes(
       app_package_name_native, domain_path_regex_native, label_native);
 }
 
 void ExternalDataUseObserverBridge::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,
+    const base::Time start_time,
+    const base::Time end_time,
     int64_t bytes_downloaded,
     int64_t bytes_uploaded) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   JNIEnv* env = base::android::AttachCurrentThread();
   DCHECK(!j_external_data_use_observer_.is_null());
 
   // End time should be greater than start time.
   int64_t start_time_milliseconds = start_time.ToJavaTime();
   int64_t end_time_milliseconds = end_time.ToJavaTime();
@@ skipping 39 matching lines @@
                  external_data_use_observer_, should_register));
 }
 
 bool RegisterExternalDataUseObserver(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace android
 
 }  // namespace chrome