Prefix string16 with base:: in ui/.

ui/views/controls/button/image_button.h

Index: ui/views/controls/button/image_button.h
diff --git a/ui/views/controls/button/image_button.h b/ui/views/controls/button/image_button.h
index 4977b06d3987143188e5646eb219e471629387cb..46ab52ed99cfcafc5a473dbc3e08b520dcd8c030 100644
--- a/ui/views/controls/button/image_button.h
+++ b/ui/views/controls/button/image_button.h
@@ -145,7 +145,7 @@ class VIEWS_EXPORT ToggleImageButton : public ImageButton {
   void SetToggledImage(ButtonState state, const gfx::ImageSkia* image);
 
   // Set the tooltip text displayed when the button is toggled.
-  void SetToggledTooltipText(const string16& tooltip);
+  void SetToggledTooltipText(const base::string16& tooltip);
 
   // Overridden from ImageButton:
   virtual const gfx::ImageSkia& GetImage(ButtonState state) const OVERRIDE;
@@ -154,7 +154,7 @@ class VIEWS_EXPORT ToggleImageButton : public ImageButton {
 
   // Overridden from View:
   virtual bool GetTooltipText(const gfx::Point& p,
-                              string16* tooltip) const OVERRIDE;
+                              base::string16* tooltip) const OVERRIDE;
   virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
 
  private:
@@ -168,7 +168,7 @@ class VIEWS_EXPORT ToggleImageButton : public ImageButton {
 
   // The parent class's tooltip_text_ is displayed when not toggled, and
   // this one is shown when toggled.
-  string16 toggled_tooltip_text_;
+  base::string16 toggled_tooltip_text_;
 
   DISALLOW_COPY_AND_ASSIGN(ToggleImageButton);
 };