Select theme resources from ResourceBundle at requested scale factor.

ui/base/resource/resource_handle.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 UI_BASE_RESOURCE_RESOURCE_HANDLE_H_
 #define UI_BASE_RESOURCE_RESOURCE_HANDLE_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/string_piece.h"
@@ skipping 11 matching lines @@
   enum TextEncodingType {
     BINARY,
     UTF8,
     UTF16
   };
 
   // The scale factors for image resources.
   static const float kScaleFactor100x;
   static const float kScaleFactor200x;
 
+  // This scale factor is used for non-image resources.
+  static const float kScaleFactorNone;

[tony, 2012/05/11 21:22:03]

Can we combine the scale factors into an enum?  The only valid values seem to be
are 1, 2 and None.  Also, I find it confusing that the variable names are 100x
and 200x since that sounds like 100 and 200 times bigger. 1x and 2x would make
more sense and match the other code.

[sail, 2012/05/11 21:28:50]

This used to be 1x and 2x but Joi made a good point that we need to support 1.4x
and 1.8x for Windows 8 Metro. Using a percentage system makes that easier to
ready.

+
   virtual ~ResourceHandle() {}
 
+  // Returns true if the DataPack contains a resource with id |resource_id|.
+  virtual bool HasResource(uint16 resource_id) const = 0;
+
   // Get resource by id |resource_id|, filling in |data|.
   // The data is owned by the DataPack object and should not be modified.
   // Returns false if the resource id isn't found.
   virtual bool GetStringPiece(uint16 resource_id,
                               base::StringPiece* data) const = 0;
 
   // Like GetStringPiece(), but returns a reference to memory.
   // Caller owns the returned object.
   virtual base::RefCountedStaticMemory* GetStaticMemory(
       uint16 resource_id) const = 0;
 
   // Get the encoding type of text resources.
   virtual TextEncodingType GetTextEncodingType() const = 0;
 
   // The scale of images in this resource pack relative to images in the 1x
   // resource pak.
   virtual float GetScaleFactor() const = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_RESOURCE_RESOURCE_HANDLE_H_