Add GrGLCreateNullInterface.cpp back to gyp, and put contents in namespace.

TBR=robertphillips@google.com

Review URL: https://codereview.chromium.org/899803004

gyp/gpu.gypi

@@ -370,6 +370,7 @@
       '<(skia_src_path)/gpu/gl/debug/SkDebugGLContext.h',
     ],
     'skgpu_null_gl_sources': [
+      '<(skia_src_path)/gpu/gl/GrGLCreateNullInterface.cpp',
       '<(skia_src_path)/gpu/gl/SkNullGLContext.cpp',
       '<(skia_include_path)/gpu/gl/SkNullGLContext.h',
     ],

src/gpu/gl/GrGLCreateNullInterface.cpp

@@ -12,6 +12,12 @@
 #include "GrGLNoOpInterface.h"
 #include "SkTLS.h"
 
+// TODO: Delete this file after chrome starts using SkNullGLContext.
+
+// added to suppress 'no previous prototype' warning and because this code is duplicated in
+// SkNullGLContext.cpp
+namespace {      
+
 class BufferObj {
 public:
     SK_DECLARE_INST_COUNT(BufferObj);
@@ -141,8 +147,6 @@ private:
 
 // Functions not declared in GrGLBogusInterface.h (not common with the Debug GL interface).
 
-namespace { // added to suppress 'no previous prototype' warning
-
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLActiveTexture(GrGLenum texture) {}
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLAttachShader(GrGLuint program, GrGLuint shader) {}
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLBeginQuery(GrGLenum target, GrGLuint id) {}