Uses and returns the fractional width in text eliding

chrome/browser/ui/autofill/autofill_popup_controller.h

 // Copyright (c) 2012 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 CHROME_BROWSER_UI_AUTOFILL_AUTOFILL_POPUP_CONTROLLER_H_
 #define CHROME_BROWSER_UI_AUTOFILL_AUTOFILL_POPUP_CONTROLLER_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 45 matching lines @@
   virtual int GetIconResourceID(const string16& resource_name) = 0;
 
   // Returns true if the given index refers to an element that can be deleted.
   virtual bool CanDelete(size_t index) const = 0;
 
   // Returns true if the given index refers to an element that is a warning
   // rather than an Autofill suggestion.
   virtual bool IsWarning(size_t index) const = 0;
 
   // Updates the bounds of the popup and initiates a redraw.
-  virtual void SetPopupBounds(const gfx::Rect& bounds) = 0;
+  virtual void SetPopupBounds(const gfx::RectF& bounds) = 0;

[sky, 2013/10/03 14:19:23]

Why do any of the changes in this file require floats? Bounds should always end
up as ints, right?

[jianli, 2013/10/03 18:42:17]

On Mac, bounds are represented as floats underneath. Since these auto-fill popup
bounds are computed based on string width, we should try to return float bounds
in order to avoid possible round-down. Otherwise, it could be possible that the
truncated bounds add up with other truncated bounds which could cause the
problem.

 
   // Returns the bounds of the item at |index| in the popup, relative to
   // the top left of the popup.
-  virtual gfx::Rect GetRowBounds(size_t index) = 0;
+  virtual gfx::RectF GetRowBounds(size_t index) = 0;
 
   // The actual bounds of the popup.
-  virtual const gfx::Rect& popup_bounds() const = 0;
+  virtual const gfx::RectF& popup_bounds() const = 0;
 
   // The view that the form field element sits in.
   virtual gfx::NativeView container_view() const = 0;
 
   // The bounds of the form field element (screen coordinates).
   virtual const gfx::RectF& element_bounds() const = 0;
 
   // If the current popup should be displayed in RTL mode.
   virtual bool IsRTL() const = 0;
 
@@ skipping 26 matching lines @@
   // Whether the view should be hidden on outside mouse presses.
   virtual bool hide_on_outside_click() const = 0;
 
  protected:
   virtual ~AutofillPopupController() {}
 };
 
 }  // namespace autofill
 
 #endif  // CHROME_BROWSER_UI_AUTOFILL_AUTOFILL_POPUP_CONTROLLER_H_