Refactoring the ownership of ui::InputMethod.

ui/aura/window_tree_host.h

Index: ui/aura/window_tree_host.h
diff --git a/ui/aura/window_tree_host.h b/ui/aura/window_tree_host.h
index 0d09093bca14112928d511225b89288b22dd973c..0f1510f8148dd45489a8c32f58306e47eedf4196 100644
--- a/ui/aura/window_tree_host.h
+++ b/ui/aura/window_tree_host.h
@@ -11,6 +11,7 @@
 #include "base/message_loop/message_loop.h"
 #include "ui/aura/aura_export.h"
 #include "ui/base/cursor/cursor.h"
+#include "ui/base/ime/input_method_delegate.h"
 #include "ui/events/event_source.h"
 #include "ui/gfx/native_widget_types.h"
 
@@ -25,6 +26,7 @@ class Transform;
 namespace ui {
 class Compositor;
 class EventProcessor;
+class InputMethod;
 class ViewProp;
 }
 
@@ -39,9 +41,10 @@ class WindowTreeHostObserver;
 // WindowTreeHost bridges between a native window and the embedded RootWindow.
 // It provides the accelerated widget and maps events from the native os to
 // aura.
-class AURA_EXPORT WindowTreeHost {
+class AURA_EXPORT WindowTreeHost : public ui::internal::InputMethodDelegate,
+                                   public ui::EventSource {
  public:
-  virtual ~WindowTreeHost();
+  ~WindowTreeHost() override;
 
   // Creates a new WindowTreeHost. The caller owns the returned value.
   static WindowTreeHost* Create(const gfx::Rect& bounds);
@@ -116,6 +119,17 @@ class AURA_EXPORT WindowTreeHost {
 
   gfx::NativeCursor last_cursor() const { return last_cursor_; }
 
+  // Gets the InputMethod instance, if NULL, creates & owns it.
+  ui::InputMethod* GetInputMethod();
+
+  // Sets the InputMethod instance, and it is not owned by this WindowTreeHost.

[sky, 2015/06/04 13:40:28]

Sets a shared unowned InputMethod. This is used when there is a singleton
InputMethod shared between multiple instances.

Can this be protected?

[Shu Chen, 2015/06/04 15:59:25]

Revised the comment.

To make it protected, a new param ui::InputMethod* needs to be added to
constructors of AshWindowTreeHostXxx. And add a new member ui::InputMethod* to
AshWindowTreeHostInitParams.

I would prefer to remain this as public because the singleton/shared InputMethod
is a temporary solution.
My later CL will try to make each AshWindowTreeHost to own a separated
InputMethod instance.

[sky, 2015/06/04 19:42:52]

Fair enough.

+  // This is to let some environment can have the singleton InputMethod
+  // instance cross multiple WindowTreeHost's (e.g. Ash).
+  void SetInputMethod(ui::InputMethod* input_method);
+
+  // Overridden from ui::internal::InputMethodDelegate:
+  bool DispatchKeyEventPostIME(const ui::KeyEvent& event) override;
+
   // Returns the EventSource responsible for dispatching events to the window
   // tree.
   virtual ui::EventSource* GetEventSource() = 0;
@@ -166,6 +180,10 @@ class AURA_EXPORT WindowTreeHost {
   // kCalled when the cursor visibility has changed.
   virtual void OnCursorVisibilityChangedNative(bool show) = 0;
 
+  // Overridden from ui::EventSource:
+  ui::EventProcessor* GetEventProcessor() override;
+  ui::EventDispatchDetails DeliverEventToProcessor(ui::Event* event) override;
+
  private:
   friend class test::WindowTreeHostTestApi;
 
@@ -192,6 +210,16 @@ class AURA_EXPORT WindowTreeHost {
 
   scoped_ptr<ui::ViewProp> prop_;
 
+  // The InputMethod instance used to process key events.
+  // If owned it, it is created in GetInputMethod() method;
+  // If not owned it, it is passed in through SetInputMethod() method.
+  ui::InputMethod* input_method_;
+
+  // Whether the InputMethod instance is owned by this WindowTreeHost.
+  // So that the destructor can determine whether to release the InputMethod

[sky, 2015/06/04 13:40:28]

Nuke second sentence.

[Shu Chen, 2015/06/04 15:59:25]

Done.

+  // instance.
+  bool owned_input_method_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHost);
 };