Reland change for aura tooltips that was revert due to build break:

ui/aura_shell/shell_tooltip_manager.h

Index: ui/aura_shell/shell_tooltip_manager.h
diff --git a/ui/aura_shell/shell_tooltip_manager.h b/ui/aura_shell/shell_tooltip_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..a9b301b60c1e8dd863814aa7e2fac39f6a7b1915
--- /dev/null
+++ b/ui/aura_shell/shell_tooltip_manager.h
@@ -0,0 +1,71 @@
+// Copyright (c) 2011 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_AURA_SHELL_SHELL_TOOLTIP_MANAGER_H_
+#define UI_AURA_SHELL_SHELL_TOOLTIP_MANAGER_H_
+#pragma once
+
+#include "base/memory/scoped_ptr.h"
+#include "base/string16.h"
+#include "base/timer.h"
+#include "ui/aura/client/tooltip_client.h"
+#include "ui/aura/event_filter.h"
+#include "ui/aura/window_observer.h"
+#include "ui/aura_shell/aura_shell_export.h"
+#include "ui/gfx/point.h"
+
+namespace aura {
+class KeyEvent;
+class MouseEvent;
+class TouchEvent;
+class Window;
+}
+
+namespace aura_shell {
+
+// ShellTooltipManager provides tooltip functionality for aura shell.
+class AURA_SHELL_EXPORT ShellTooltipManager : public aura::TooltipClient,
+                                              public aura::EventFilter,
+                                              public aura::WindowObserver {
+ public:
+  ShellTooltipManager();
+  virtual ~ShellTooltipManager();
+
+  // Overridden from aura::TooltipClient.
+  void UpdateTooltip(aura::Window* target);
+
+  // Overridden from aura::EventFilter.
+  virtual bool PreHandleKeyEvent(aura::Window* target,
+                                 aura::KeyEvent* event) OVERRIDE;
+  virtual bool PreHandleMouseEvent(aura::Window* target,
+                                   aura::MouseEvent* event) OVERRIDE;
+  virtual ui::TouchStatus PreHandleTouchEvent(aura::Window* target,
+                                              aura::TouchEvent* event) OVERRIDE;
+
+  // Overridden from aura::WindowObserver.
+  virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
+
+ private:
+  class Tooltip;
+
+  void TooltipTimerFired();
+
+  // Updates the tooltip if required (if there is any change in the tooltip
+  // text or the aura::Window.
+  void UpdateIfRequired();
+
+  aura::Window* tooltip_window_;
+  string16 tooltip_text_;
+  scoped_ptr<Tooltip> tooltip_;
+
+  base::RepeatingTimer<ShellTooltipManager> tooltip_timer_;
+
+  gfx::Point curr_mouse_loc_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShellTooltipManager);
+};
+
+}  // namespace aura_shell
+
+#endif  // UI_AURA_SHELL_SHELL_TOOLTIP_MANAGER_H_