Add a query function for the scaling feature.

ppapi/cpp/dev/graphics_2d_dev.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 PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_
 #define PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_
 
 #include "ppapi/cpp/graphics_2d.h"
 
 namespace pp {
 
 // Graphics2DDev is a version of Graphics2D that exposes under-development  APIs
 // for HiDPI
-class Graphics2DDev : public Graphics2D {
+class Graphics2D_Dev : public Graphics2D {

[Josh Horwich, 2012/08/21 23:53:29]

Just a reminder that we'll want to quickly rev clients to account for the rename
(e.g. PDF Viewer)

Should we do both this and ViewDev -> View_Dev at the same time then? I don't
have a strong opinion either way.

  public:
   /// Default constructor for creating an is_null()
-  /// <code>Graphics2DDev</code> object.
-  Graphics2DDev() : Graphics2D() {}
+  /// <code>Graphics2D_Dev</code> object.
+  Graphics2D_Dev() : Graphics2D() {}
 
   // Constructor for creating a <code>Graphics2DDev</code> object from an
   // existing <code>Graphics2D</code> object.
-  Graphics2DDev(const Graphics2D& other) : Graphics2D(other) {}
+  Graphics2D_Dev(const Graphics2D& other) : Graphics2D(other) {}
 
-  virtual ~Graphics2DDev() {}
+  virtual ~Graphics2D_Dev() {}
+
+  /// Returns true if SetScale and GetScale are supported. False if not.
+  static bool SupportsScale();
 
   /// SetScale() sets the scale factor that will be applied when painting the
   /// graphics context onto the output device. Typically, if rendering at device
   /// resolution is desired, the context would be created with the width and
   /// height scaled up by the view's GetDeviceScale and SetScale called with a
   /// scale of 1.0 / GetDeviceScale(). For example, if the view resource passed
   /// to DidChangeView has a rectangle of (w=200, h=100) and a device scale of
   /// 2.0, one would call Create with a size of (w=400, h=200) and then call
   /// SetScale with 0.5. One would then treat each pixel in the context as a
   /// single device pixel.
   ///
   /// @param[in] scale The scale to apply when painting.
   ///
   /// @return Returns <code>true</code> on success or <code>false</code>
   /// if the resource is invalid or the scale factor is 0 or less.
   bool SetScale(float scale);
 
   /// GetScale() gets the scale factor that will be applied when painting the
   /// graphics context onto the output device.
   ///
   /// @return Returns the scale factor for the graphics context. If the resource
   /// is invalid, 0.0 will be returned.
   float GetScale();
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_