Pass MetricsServiceClient into MetricsService, and create a simple stubbed TestMetricsServiceClient…

chrome/browser/metrics/chrome_metrics_service_client.cc

 // Copyright 2014 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/metrics/chrome_metrics_service_client.h"
 
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/google/google_util.h"
 #include "chrome/browser/ui/browser_otr_state.h"
@@ skipping 15 matching lines @@
       return metrics::SystemProfileProto::CHANNEL_BETA;
     case chrome::VersionInfo::CHANNEL_STABLE:
       return metrics::SystemProfileProto::CHANNEL_STABLE;
   }
   NOTREACHED();
   return metrics::SystemProfileProto::CHANNEL_UNKNOWN;
 }
 
 }  // namespace
 
-ChromeMetricsServiceClient::ChromeMetricsServiceClient()
-    : MetricsServiceClient() {
+ChromeMetricsServiceClient::ChromeMetricsServiceClient() {
 }
 
 ChromeMetricsServiceClient::~ChromeMetricsServiceClient() {
 }
 
 void ChromeMetricsServiceClient::SetClientID(const std::string& client_id) {
   crash_keys::SetClientID(client_id);
 }
 
 bool ChromeMetricsServiceClient::IsOffTheRecordSessionActive() {
   return !chrome::IsOffTheRecordSessionActive();
 }
 
 std::string ChromeMetricsServiceClient::GetApplicationLocale() {
   return g_browser_process->GetApplicationLocale();
 }
 
 bool ChromeMetricsServiceClient::GetBrand(std::string* brand_code) {
   return google_util::GetBrand(brand_code);
 }
 
 metrics::SystemProfileProto::Channel ChromeMetricsServiceClient::GetChannel() {
   return AsProtobufChannel(chrome::VersionInfo::GetChannel());
 }
 
 std::string ChromeMetricsServiceClient::GetVersionString() {
   // TODO(asvitkine): Move over from metrics_log.cc
   return std::string();
 }