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

mojo/shell/package_manager/capability_filter_content_handler_unittest.cc

Index: mojo/shell/package_manager/capability_filter_content_handler_unittest.cc
diff --git a/mojo/shell/package_manager/capability_filter_content_handler_unittest.cc b/mojo/shell/package_manager/capability_filter_content_handler_unittest.cc
index 2268a7e9bc15ab439ae65bdff977671a11f3cfe3..7e9ace8500a5a08cf468b0735aca0e7c368abb59 100644
--- a/mojo/shell/package_manager/capability_filter_content_handler_unittest.cc
+++ b/mojo/shell/package_manager/capability_filter_content_handler_unittest.cc
@@ -81,14 +81,12 @@ class TestContentHandler : public ApplicationDelegate,
                            public InterfaceFactory<mojom::ContentHandler>,
                            public mojom::ContentHandler {
  public:
-  TestContentHandler() : app_(nullptr) {}
+  TestContentHandler() {}
   ~TestContentHandler() override {}
 
  private:
   // Overridden from ApplicationDelegate:
-  void Initialize(ApplicationImpl* app) override {
-    app_ = app;
-  }
+  void Initialize(Shell* shell, const std::string& url, uint32_t id) override {}
   bool AcceptConnection(ApplicationConnection* connection) override {
     connection->AddService<mojom::ContentHandler>(this);
     return true;
@@ -112,7 +110,6 @@ class TestContentHandler : public ApplicationDelegate,
     destruct_callback.Run();
   }
 
-  ApplicationImpl* app_;
   WeakBindingSet<mojom::ContentHandler> bindings_;
   ScopedVector<ApplicationDelegate> embedded_app_delegates_;
   ScopedVector<ApplicationImpl> embedded_apps_;