Add fake for InstanceIDWithSubtype.java, in order to re-use unit test

components/gcm_driver/instance_id/instance_id_driver_unittest.cc

Index: components/gcm_driver/instance_id/instance_id_driver_unittest.cc
diff --git a/components/gcm_driver/instance_id/instance_id_driver_unittest.cc b/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
index 8997296aca9b1dad49e6749524421ca3094672b6..f6184a6b3baa45b328b6aa7c494681da2335e1b2 100644
--- a/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
+++ b/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
@@ -17,6 +17,11 @@
 #include "components/gcm_driver/instance_id/instance_id.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+#if defined(OS_ANDROID)
+#include "components/gcm_driver/instance_id/instance_id_android.h"
+#include "content/public/test/nested_message_pump_android.h"
+#endif  // OS_ANDROID
+
 namespace instance_id {
 
 namespace {
@@ -51,6 +56,7 @@ class InstanceIDDriverTest : public testing::Test {
   ~InstanceIDDriverTest() override;
 
   // testing::Test:
+  void TearDown() override;
   void SetUp() override;
 
   void WaitForAsyncOperation();
@@ -81,7 +87,7 @@ class InstanceIDDriverTest : public testing::Test {
   void GetTokenCompleted(const std::string& token, InstanceID::Result result);
   void DeleteTokenCompleted(InstanceID::Result result);
 
-  base::MessageLoopForUI message_loop_;
+  scoped_ptr<base::MessageLoop> message_loop_;
   scoped_ptr<FakeGCMDriverForInstanceID> gcm_driver_;
   scoped_ptr<InstanceIDDriver> driver_;
 
@@ -99,16 +105,34 @@ class InstanceIDDriverTest : public testing::Test {
 InstanceIDDriverTest::InstanceIDDriverTest()
     : result_(InstanceID::UNKNOWN_ERROR),
       async_operation_completed_(false) {
+#if defined(OS_ANDROID)
+  // Need a NestedMessagePumpAndroid so WaitForAsyncOperation's RunLoop will run
+  // InstanceIDWithSubtype.java's AsyncTask onPostExecute methods.
+  message_loop_.reset(new base::MessageLoop(
+      scoped_ptr<base::MessagePump>(new content::NestedMessagePumpAndroid())));
+  static_cast<base::MessageLoopForUI*>(message_loop_.get())->Start();

[Peter Beverloo, 2016/04/11 14:57:05]

You're casting an instance of base::MessageLoop to a subclass you know it to not
be an instance of...?

[johnme, 2016/04/14 18:32:42]

Bizarrely, this seems to be what you're supposed to do. It's what Kristian does
in:

https://code.google.com/p/chromium/codesearch#chromium/src/base/android/java_...

And message_loop.h contains the following:

// Do not add any member variables to MessageLoopForUI!  This is important b/c
// MessageLoopForUI is often allocated via MessageLoop(TYPE_UI).  Any extra
// data that you need should be stored on the MessageLoop's pump_ instance.
static_assert(sizeof(MessageLoop) == sizeof(MessageLoopForUI),
              "MessageLoopForUI should not have extra member variables");

Anyway, thankfully this code all got removed now I stopped using
NestedMessagePumpAndroid.

+#else
+  message_loop_.reset(new base::MessageLoopForUI());
+#endif  // OS_ANDROID
 }
 
 InstanceIDDriverTest::~InstanceIDDriverTest() {
 }
 
 void InstanceIDDriverTest::SetUp() {
+#if defined(OS_ANDROID)
+  InstanceIDAndroid::ClearDataAndSetUseFakeForTesting(true);
+#endif  // OS_ANDROID
   gcm_driver_.reset(new FakeGCMDriverForInstanceID);
   RecreateInstanceIDDriver();
 }
 
+void InstanceIDDriverTest::TearDown() {
+#if defined(OS_ANDROID)
+  InstanceIDAndroid::ClearDataAndSetUseFakeForTesting(false);
+#endif  // OS_ANDROID
+}
+
 void InstanceIDDriverTest::RecreateInstanceIDDriver() {
   driver_.reset(new InstanceIDDriver(gcm_driver_.get()));
 }