Add DeviceSettingProvider unit tests.

chrome/test/base/testing_browser_process.h

Index: chrome/test/base/testing_browser_process.h
diff --git a/chrome/test/base/testing_browser_process.h b/chrome/test/base/testing_browser_process.h
index 93044bb508d3b198df79534cf3fbb21a83aebba4..19963694f6bda40a445d5c1a9f894128c570350f 100644
--- a/chrome/test/base/testing_browser_process.h
+++ b/chrome/test/base/testing_browser_process.h
@@ -114,6 +114,7 @@ class TestingBrowserProcess : public BrowserProcess {
   void SetIOThread(IOThread* io_thread);
   void SetBrowserPolicyConnector(policy::BrowserPolicyConnector* connector);
   void SetSafeBrowsingService(SafeBrowsingService* sb_service);
+  void SetMetricsService(MetricsService* service);
 
  private:
   scoped_ptr<content::NotificationService> notification_service_;
@@ -134,6 +135,7 @@ class TestingBrowserProcess : public BrowserProcess {
   scoped_ptr<prerender::PrerenderTracker> prerender_tracker_;
   IOThread* io_thread_;
   scoped_refptr<SafeBrowsingService> sb_service_;
+  scoped_ptr<MetricsService> metrics_service_;
 
   DISALLOW_COPY_AND_ASSIGN(TestingBrowserProcess);
 };