Cleanup namespace usage in platform/graphics/[G-S]*

Source/platform/graphics/Gradient.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 247 matching lines @@
         m_gradient = adoptRef(SkGradientShader::CreateLinear(pts, colors.data(), pos.data(), static_cast<int>(countUsed), tile, shouldDrawInPMColorSpace, &localMatrix));
     }
 
     if (!m_gradient) {
         // use last color, since our "geometry" was degenerate (e.g. radius==0)
         m_gradient = adoptRef(new SkColorShader(colors[countUsed - 1]));
     }
     return m_gradient.get();
 }
 
-} //namespace
+} // namespace blink