Support uninstalling ARC app from Chrome launcher

components/arc/test/fake_app_instance.cc

Index: components/arc/test/fake_app_instance.cc
diff --git a/components/arc/test/fake_app_instance.cc b/components/arc/test/fake_app_instance.cc
index 8f6fe71498544f4a84cbfd9388c462eb5689dfa5..56daea231af3f9b3d60b84a6b55a6083c2d2b667 100644
--- a/components/arc/test/fake_app_instance.cc
+++ b/components/arc/test/fake_app_instance.cc
@@ -133,4 +133,9 @@ void FakeAppInstance::CanHandleResolution(const mojo::String& package_name,
   callback.Run(true);
 }
 
+void FakeAppInstance::UninstallApp(const mojo::String& package_name,
+                                   const UninstallAppCallback& callback) {
+  callback.Run("success");

[dcheng, 2016/03/08 00:47:23]

Hmm... won't OnUninstallAppResponse treat this as a failure since it checks if
the string is non-null?

[victorhsieh0, 2016/03/08 01:05:29]

Not sure why my change is gone :(  This isn't called today, but for correctness
it's calling with nullptr now.

+}
+
 }  // namespace arc