Export stability metrics to UMA from Blimp engine

blimp/engine/common/blimp_browser_context_unittest.cc

Index: blimp/engine/common/blimp_browser_context_unittest.cc
diff --git a/blimp/engine/common/blimp_browser_context_unittest.cc b/blimp/engine/common/blimp_browser_context_unittest.cc
index 5550c6ef80d4a7c998fcceb0bcc5d1775bb2ab8c..3688268a2406dd000dde1286276658f4e04f758a 100644
--- a/blimp/engine/common/blimp_browser_context_unittest.cc
+++ b/blimp/engine/common/blimp_browser_context_unittest.cc
@@ -7,6 +7,7 @@
 #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"
@@ -20,6 +21,9 @@ class BlimpBrowserContextTest : public testing::Test {
 
  protected:
   void SetUp() override {
+    // Set up NotificationService
+    notification_service_.reset(content::NotificationService::Create());
+
     base::SetRecordActionTaskRunner(
         base::MessageLoop::current()->task_runner());
     // Create BlimpBrowserContext.
@@ -36,6 +40,7 @@ class BlimpBrowserContextTest : public testing::Test {
 
  private:
   content::TestBrowserThreadBundle thread_bundle_;
+  std::unique_ptr<content::NotificationService> notification_service_;
   net::NetLog net_log_;
   std::unique_ptr<BlimpBrowserContext> browser_context_;