Redesigns the text input focus handling.

ui/base/ime/text_input_focus_manager.h

Index: ui/base/ime/text_input_focus_manager.h
diff --git a/ui/base/ime/text_input_focus_manager.h b/ui/base/ime/text_input_focus_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..54d66944c8c370822f5bef2f4bd2afbc1f6d89af
--- /dev/null
+++ b/ui/base/ime/text_input_focus_manager.h
@@ -0,0 +1,47 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_BASE_IME_TEXT_INPUT_FOCUS_MANAGER_H_
+#define UI_BASE_IME_TEXT_INPUT_FOCUS_MANAGER_H_
+
+#include "base/macros.h"
+#include "ui/base/ui_base_export.h"
+
+template <typename T> struct DefaultSingletonTraits;
+
+namespace ui {
+
+class TextInputClient;
+
+// The TextInputFocusManager class manages which instance of TextInputClient

[msw, 2014/03/11 00:58:50]

nit: remove "The TextInputFocusManager class"; consider "Manages the focused
TextInputClient across windows and their contents."

[Yuki, 2014/03/11 15:27:37]

Done.

+// has the text input focus.
+class UI_BASE_EXPORT TextInputFocusManager {
+ public:
+  virtual ~TextInputFocusManager();

[msw, 2014/03/11 00:58:50]

nit: I don't think this needs to be virtual or public.

[Yuki, 2014/03/11 15:27:37]

Done.

+
+  static TextInputFocusManager* GetInstance();
+
+  // Returns the currently focused text input client or NULL.
+  TextInputClient* GetFocusedTextInputClient();
+
+  // Changes the text input focus to |text_input_client|.
+  void SetFocusedTextInputClient(TextInputClient* text_input_client);

[msw, 2014/03/11 00:58:50]

nit: consider "FocusTextInputClient"

[Yuki, 2014/03/11 15:27:37]

Done.

+
+  // Removes the text input focus from |text_input_client|.  If
+  // |text_input_client| was not focused, does nothing.
+  void UnsetFocusedTextInputClient(TextInputClient* text_input_client);

[msw, 2014/03/11 00:58:50]

nit: consider "BlurTextInputClient" or "UnfocusTextInputClient"

[Yuki, 2014/03/11 15:27:37]

Done.

+
+ private:
+  TextInputFocusManager();
+
+  TextInputClient* focused_text_input_client_;

[msw, 2014/03/11 00:58:50]

Is this better than views::FocusManager having a static TextInputClient* member?

[Yuki, 2014/03/11 15:27:37]

ui::InputMethod cannot access to views.  ui::InputMethod and ui::TextInputClient
were designed not to depend on views or anything else.  So
ui::TextInputFocusManager should be, too.

In the design discussion on the doc, people wanted them to be independent from
views.

[msw, 2014/03/11 23:24:37]

Sounds good.

+
+  friend struct DefaultSingletonTraits<TextInputFocusManager>;

[msw, 2014/03/11 00:58:50]

nit: friend types are commonly declared at the top of the private section.

[Yuki, 2014/03/11 15:27:37]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(TextInputFocusManager);
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_IME_TEXT_INPUT_FOCUS_MANAGER_H_