Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/metrics/ios_chrome_stability_metrics_provider_unittest.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 "ios/chrome/browser/metrics/ios_chrome_stability_metrics_provider.h"
 
 #include "base/macros.h"
 #include "components/metrics/proto/system_profile.pb.h"
 #include "components/prefs/pref_service.h"
 #include "components/prefs/scoped_user_pref_update.h"
 #include "components/prefs/testing_pref_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 class IOSChromeStabilityMetricsProviderTest : public testing::Test {
  protected:
   IOSChromeStabilityMetricsProviderTest()
       : prefs_(new TestingPrefServiceSimple) {
     metrics::StabilityMetricsHelper::RegisterPrefs(prefs()->registry());
   }
 
   TestingPrefServiceSimple* prefs() { return prefs_.get(); }
 
  private:
-  scoped_ptr<TestingPrefServiceSimple> prefs_;
+  std::unique_ptr<TestingPrefServiceSimple> prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromeStabilityMetricsProviderTest);
 };
 
 }  // namespace
 
 TEST_F(IOSChromeStabilityMetricsProviderTest, LogLoadStart) {
   IOSChromeStabilityMetricsProvider provider(prefs());
 
   // A load should not increment metrics if recording is disabled.
@@ skipping 39 matching lines @@
   provider.OnRecordingEnabled();
   provider.LogRendererCrash();
 
   system_profile.Clear();
   provider.ProvideStabilityMetrics(&system_profile);
 
   EXPECT_EQ(1, system_profile.stability().renderer_crash_count());
   EXPECT_EQ(0, system_profile.stability().renderer_failed_launch_count());
   EXPECT_EQ(0, system_profile.stability().extension_renderer_crash_count());
 }