Export stability metrics to UMA from Blimp engine

blimp/engine/common/blimp_browser_context_unittest.cc

 // Copyright 2016 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 "blimp/engine/common/blimp_browser_context.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/user_metrics.h"
 #include "components/metrics/metrics_service.h"
+#include "content/public/browser/notification_service.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "net/log/net_log.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blimp {
 namespace engine {
 
 class BlimpBrowserContextTest : public testing::Test {
  public:
   BlimpBrowserContextTest() {}
 
  protected:
   void SetUp() override {
+    // Set up NotificationService
+    notification_service_.reset(content::NotificationService::Create());
+
     base::SetRecordActionTaskRunner(
         base::MessageLoop::current()->task_runner());
     // Create BlimpBrowserContext.
     browser_context_.reset(new BlimpBrowserContext(false /* off_the_record */,
                                                    &net_log_));
   }
 
   void TearDown() override {
     // Clears static variable in MetricsService
     metrics::MetricsService::SetExecutionPhase(
         metrics::MetricsService::UNINITIALIZED_PHASE,
         browser_context_->GetPrefService());
   }
 
  private:
   content::TestBrowserThreadBundle thread_bundle_;
+  std::unique_ptr<content::NotificationService> notification_service_;
   net::NetLog net_log_;
   std::unique_ptr<BlimpBrowserContext> browser_context_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpBrowserContextTest);
 };
 
 TEST_F(BlimpBrowserContextTest, CtorDtor) {
   // Covers construction and destruction of BlimpBrowserContext and
   // associated metrics setup and teardown.
 }
 
 }  // namespace engine
 }  // namespace blimp