get webframe_impl.cc to compile on linux

base/gfx/bitmap_platform_device_linux.h

Index: base/gfx/bitmap_platform_device_linux.h
diff --git a/base/gfx/bitmap_platform_device_linux.h b/base/gfx/bitmap_platform_device_linux.h
index 2bb5a2400d87de7832e174583055ff913c477802..f459d42342194efe51eb87d1b606e05939595efa 100644
--- a/base/gfx/bitmap_platform_device_linux.h
+++ b/base/gfx/bitmap_platform_device_linux.h
@@ -24,6 +24,9 @@ class BitmapPlatformDeviceLinux : public PlatformDeviceLinux {
   /// the Windows and Mac versions of this class do.
   BitmapPlatformDeviceLinux(const SkBitmap& other);
   virtual ~BitmapPlatformDeviceLinux();
+
+  // A stub copy constructor.  Needs to be properly implemented.
+  BitmapPlatformDeviceLinux(const BitmapPlatformDeviceLinux& other);
 };
 
 }  // namespace gfx