Mojo: Make overriding OnConnectionError optional

Using mojo::Application::AddService<ServiceImpl> results in the system taking care of error handling for you. There's no need to force ServiceImpl to override OnConnectionError in this case.

Review URL: https://codereview.chromium.org/289873008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271287 0039d316-1c4b-4281-b951-d872f2087c98

mojo/examples/launcher/launcher.cc

@@ -206,9 +206,6 @@ class LauncherImpl : public InterfaceImpl<Launcher>,
         base::Bind(&LauncherImpl::HostContextCreated, base::Unretained(this))));
   }
 
-  // Overridden from InterfaceImpl:
-  virtual void OnConnectionError() OVERRIDE {}
-
  private:
   // Overridden from Launcher:
   virtual void Show() OVERRIDE {

mojo/public/cpp/bindings/interface_impl.h

@@ -21,17 +21,19 @@ class InterfaceImpl : public internal::InterfaceImplBase<Interface> {
   InterfaceImpl() : internal_state_(this) {}
   virtual ~InterfaceImpl() {}
 
-  // Subclasses can override this to handle post connection initialization.
-  virtual void OnConnectionEstablished() {}
+  // Returns a proxy to the client interface. This is null upon construction,
+  // and becomes non-null after OnClientConnected. NOTE: It remains non-null
+  // until this instance is deleted.
+  Client* client() { return internal_state_.client(); }
 
-  // Subclasses must handle connection errors.
-  virtual void OnConnectionError() = 0;
+  // Called when the client has connected to this instance.
+  virtual void OnConnectionEstablished() {}
 
-  // We override SetClient here so subclasses don't each have to.
-  virtual void SetClient(Client* client) MOJO_OVERRIDE {
-    internal_state_.set_client(client);
-  }
-  Client* client() { return internal_state_.client(); }
+  // Called when the client is no longer connected to this instance. NOTE: The
+  // client() method continues to return a non-null pointer after this method
+  // is called. After this method is called, any method calls made on client()
+  // will be silently ignored.
+  virtual void OnConnectionError() {}
 
   // DO NOT USE. Exposed only for internal use and for testing.
   internal::InterfaceImplState<Interface>* internal_state() {
@@ -39,6 +41,9 @@ class InterfaceImpl : public internal::InterfaceImplBase<Interface> {
   }
 
  private:
+  virtual void SetClient(Client* client) MOJO_OVERRIDE {
+    internal_state_.set_client(client);
+  }
   internal::InterfaceImplState<Interface> internal_state_;
   MOJO_DISALLOW_COPY_AND_ASSIGN(InterfaceImpl);
 };

mojo/service_manager/service_manager_unittest.cc

@@ -34,10 +34,6 @@ class TestServiceImpl : public InterfaceImpl<TestService> {
     --context_->num_impls;
   }
 
-  // InterfaceImpl<TestService> implementation.
-  virtual void OnConnectionError() OVERRIDE {
-  }
-
   // TestService implementation:
   virtual void Test(const mojo::String& test_string) OVERRIDE {
     context_->last_test_string = test_string.To<std::string>();

mojo/services/dbus_echo/dbus_echo_service.cc

@@ -21,8 +21,6 @@ class EchoServiceImpl : public mojo::InterfaceImpl<mojo::EchoService> {
   EchoServiceImpl() {}
   virtual ~EchoServiceImpl() {}
 
-  virtual void OnConnectionError() OVERRIDE {}
-
  protected:
   virtual void Echo(
       const mojo::String& in_to_echo,

mojo/services/native_viewport/native_viewport_service.cc

@@ -41,8 +41,6 @@ class NativeViewportImpl
     native_viewport_.reset();
   }
 
-  virtual void OnConnectionError() OVERRIDE {}
-
   virtual void Create(const Rect& bounds) OVERRIDE {
     native_viewport_ =
         services::NativeViewport::Create(context_, this);

mojo/services/view_manager/view_manager_connection.cc

@@ -70,8 +70,6 @@ void ViewManagerConnection::OnConnectionEstablished() {
       Array<INode>::From(to_send));
 }
 
-void ViewManagerConnection::OnConnectionError() {}
-
 const Node* ViewManagerConnection::GetNode(const NodeId& id) const {
   if (id_ == id.connection_id) {
     NodeMap::const_iterator i = node_map_.find(id.node_id);

mojo/services/view_manager/view_manager_connection.h

@@ -40,7 +40,6 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerConnection
   virtual ~ViewManagerConnection();
 
   virtual void OnConnectionEstablished() MOJO_OVERRIDE;
-  virtual void OnConnectionError() MOJO_OVERRIDE;
 
   TransportConnectionId id() const { return id_; }