Fix extension browsertests to correctly use ShellCrApplication.

If NSApp is used prior to instantiation of the NSApplication subclass, then the
subclass will never be instantiated.

This CL adds a CHECK to confirm that the subclass is correctly instantiated.

This CL found several tests which were unnecessarily instantiating a UI Message
Loop early in the lifetime gtest subclass, which ends up calling NSApp prior to
NSApplication subclass instantiation.

Change-Id: I8868d253b6ec6eff4f8ecdda3176d839aa1826a5
Reviewed-on: https://chromium-review.googlesource.com/1246861Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594436}

extensions/browser/api/system_memory/system_memory_apitest.cc

@@ -28,14 +28,6 @@ class SystemMemoryApiTest : public ShellApiTest {
  public:
   SystemMemoryApiTest() {}
   ~SystemMemoryApiTest() override {}
-
-  void SetUpInProcessBrowserTestFixture() override {
-    ShellApiTest::SetUpInProcessBrowserTestFixture();
-    message_loop_.reset(new base::MessageLoopForUI);
-  }
-
- private:
-  std::unique_ptr<base::MessageLoop> message_loop_;
 };
 
 IN_PROC_BROWSER_TEST_F(SystemMemoryApiTest, Memory) {

extensions/browser/api/system_storage/system_storage_apitest.cc

@@ -78,11 +78,6 @@ class SystemStorageApiTest : public extensions::ShellApiTest {
     TestStorageMonitor::CreateForBrowserTests();
   }
 
-  void SetUpInProcessBrowserTestFixture() override {
-    ShellApiTest::SetUpInProcessBrowserTestFixture();
-    message_loop_.reset(new base::MessageLoopForUI);
-  }
-
   void SetUpAllMockStorageDevices() {
     for (size_t i = 0; i < arraysize(kTestingData); ++i) {
       AttachRemovableStorage(kTestingData[i]);
@@ -99,9 +94,6 @@ class SystemStorageApiTest : public extensions::ShellApiTest {
   void DetachRemovableStorage(const std::string& id) {
     StorageMonitor::GetInstance()->receiver()->ProcessDetach(id);
   }
-
- private:
-  std::unique_ptr<base::MessageLoop> message_loop_;
 };
 
 IN_PROC_BROWSER_TEST_F(SystemStorageApiTest, Storage) {

extensions/shell/app/shell_main_delegate_mac.mm

@@ -11,6 +11,11 @@ namespace extensions {
 void ShellMainDelegate::PreCreateMainMessageLoop() {
   // Force the NSApplication subclass to be used.
   [ShellCrApplication sharedApplication];
+
+  // If there was an invocation to NSApp prior to this method, then the NSApp
+  // will not be a ShellCrApplication, but will instead be an NSApplication.
+  // This is undesirable and we must enforce that this doesn't happen.
+  CHECK([NSApp isKindOfClass:[ShellCrApplication class]]);
 }
 
 }  // namespace extensions