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

Source/platform/graphics/StrokeData.cpp

 // 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:
 //
 //    * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //    * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
@@ skipping 93 matching lines @@
                 }
             }
             SkScalar dashLengthSk = SkIntToScalar(dashLength);
             SkScalar intervals[2] = { dashLengthSk, dashLengthSk };
             RefPtr<SkDashPathEffect> pathEffect = adoptRef(SkDashPathEffect::Create(intervals, 2, SkIntToScalar(phase)));
             paint->setPathEffect(pathEffect.get());
         }
     }
 }
 
-} // namespace
+} // namespace blink