Use RenderText directly to draw tooltip

ui/views/corewm/tooltip_aura.h

 // Copyright 2013 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_VIEWS_COREWM_TOOLTIP_AURA_H_
 #define UI_VIEWS_COREWM_TOOLTIP_AURA_H_
 
 #include "ui/gfx/screen_type_delegate.h"
-#include "ui/views/controls/label.h"
 #include "ui/views/corewm/tooltip.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace gfx {
 class FontList;
+class Size;
 }  // namespace gfx
 
 namespace views {
 
 class Widget;
 
 namespace corewm {
 
 // Implementation of Tooltip that shows the tooltip using a Widget and Label.
 class VIEWS_EXPORT TooltipAura : public Tooltip, public WidgetObserver {
  public:
   TooltipAura();
   ~TooltipAura() override;
 
-  // Trims the tooltip to fit in the width |max_width|, setting |text| to the
-  // clipped result, |width| to the width (in pixels) of the clipped text
-  // and |line_count| to the number of lines of text in the tooltip. |font_list|
-  // is used to layout |text|. |max_width| comes from GetMaxWidth().
-  static void TrimTooltipToFit(const gfx::FontList& font_list,
-                               int max_width,
-                               base::string16* text,
-                               int* width,
-                               int* line_count);
+ private:
+  class TooltipView;
 
- private:
   // Adjusts the bounds given by the arguments to fit inside the desktop
   // and applies the adjusted bounds to the label_.
   void SetTooltipBounds(const gfx::Point& mouse_pos,
                         const gfx::Size& tooltip_size);
 
   // Destroys |widget_|.
   void DestroyWidget();
 
   // Tooltip:
   int GetMaxWidth(const gfx::Point& location,
                   aura::Window* context) const override;
   void SetText(aura::Window* window,
                const base::string16& tooltip_text,
                const gfx::Point& location) override;
   void Show() override;
   void Hide() override;
   bool IsVisible() override;
 
   // WidgetObserver:
   void OnWidgetDestroying(Widget* widget) override;
 
-  // The label showing the tooltip.
-  Label label_;
+  // The view showing the tooltip.
+  TooltipView* tooltip_view_;
 
   // The widget containing the tooltip. May be NULL.
   Widget* widget_;
 
   // The window we're showing the tooltip for. Never NULL and valid while
   // showing.
   aura::Window* tooltip_window_;
 
   DISALLOW_COPY_AND_ASSIGN(TooltipAura);
 };
 
 }  // namespace corewm
 }  // namespace views
 
 #endif  // UI_VIEWS_COREWM_TOOLTIP_AURA_H_