Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

mojo/shell/capability_filter_test.h

Index: mojo/shell/capability_filter_test.h
diff --git a/mojo/shell/capability_filter_test.h b/mojo/shell/capability_filter_test.h
index 394c842e5bea7f06ed93ff717e5cac41d4bfa5d7..459cfe87e77536f38f6efef3aedd6bc61b14a6a3 100644
--- a/mojo/shell/capability_filter_test.h
+++ b/mojo/shell/capability_filter_test.h
@@ -28,12 +28,13 @@ class TestApplication : public ApplicationDelegate {
 
  private:
   // Overridden from ApplicationDelegate:
-  void Initialize(ApplicationImpl* app) override;
+  void Initialize(Shell* shell, const std::string& url, uint32_t id) override;
   bool AcceptConnection(ApplicationConnection* connection) override;
 
   void ConnectionClosed(const std::string& service_url);
 
-  ApplicationImpl* app_;
+  Shell* shell_;
+  std::string url_;
   ValidatorPtr validator_;
   scoped_ptr<ApplicationConnection> connection1_;
   scoped_ptr<ApplicationConnection> connection2_;