[Mac] Wrap NSUserActivity begin/end so that it can be called from common files

content/common/mac/app_nap_activity_unittest.mm

+// Copyright 2017 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 "content/common/mac/app_nap_activity.h"
+
+#include "testing/gtest_mac.h"
+#include "testing/platform_test.h"
+#import "third_party/ocmock/OCMock/OCMock.h"
+#include "third_party/ocmock/gtest_support.h"
+
+class AppNapActivityTest : public PlatformTest {};
+
+TEST_F(AppNapActivityTest, StoresAssertion) {
+  const NSActivityOptions expectedOptions =
+      (NSActivityUserInitiatedAllowingIdleSystemSleep |
+       NSActivityLatencyCritical) &
+      ~(NSActivitySuddenTerminationDisabled |
+        NSActivityAutomaticTerminationDisabled);
+  id processInfoMock =
+      [OCMockObject partialMockForObject:[NSProcessInfo processInfo]];
+  id assertion = @"An activity assertion";
+  [[[processInfoMock expect] andReturn:assertion]
+      beginActivityWithOptions:expectedOptions
+                        reason:OCMOCK_ANY];
+
+  content::AppNapActivity activity;
+  activity.Begin();
+
+  EXPECT_OCMOCK_VERIFY(processInfoMock);
+
+  [[processInfoMock expect] endActivity:assertion];
+
+  activity.End();
+
+  EXPECT_OCMOCK_VERIFY(processInfoMock);
+  [processInfoMock stopMocking];
+}