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..4e5f2b36bb1ea6d3bef08c6c6454d038a9d178b6
--- /dev/null
+++ b/ui/base/ime/text_input_focus_manager.h
@@ -0,0 +1,45 @@
+// 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;
+
+// Manages the focused TextInputClient across windows and their contents.

[Seigo Nonaka, 2014/03/13 12:13:26]

This class seems not thread safe and only designed for UI thread, right?

If so, please add Thread Checker

[Yuki, 2014/03/14 15:25:22]

Unfortunately, either of ui/base and ui/views cannot depend on
content/public/browser, so we cannot use a thread checker.

[tfarina, 2014/03/14 19:58:56]

I'd say, 'hopefuly' :)

[Seigo Nonaka, 2014/03/17 18:08:07]

thread checker is in base/threading so you can use it in anywhere :)

[Yuki, 2014/04/16 09:24:08]

Done.

+class UI_BASE_EXPORT TextInputFocusManager {
+ public:
+  static TextInputFocusManager* GetInstance();
+
+  // Returns the currently focused text input client or NULL.
+  TextInputClient* GetFocusedTextInputClient();
+
+  // Changes the text input focus to |text_input_client|.
+  void FocusTextInputClient(TextInputClient* text_input_client);
+
+  // Removes the text input focus from |text_input_client|.  If
+  // |text_input_client| was not focused, does nothing.
+  void BlurTextInputClient(TextInputClient* text_input_client);
+
+ private:
+  friend struct DefaultSingletonTraits<TextInputFocusManager>;
+
+  TextInputFocusManager();
+  ~TextInputFocusManager();
+
+  TextInputClient* focused_text_input_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(TextInputFocusManager);
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_IME_TEXT_INPUT_FOCUS_MANAGER_H_