Various minor cross-platform changes

src/gpu/gl/GrGLGpu.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLGpu.h"
 #include "GrGLGLSL.h"
@@ skipping 546 matching lines @@
         ElevateDrawPreference(drawPreference, kGpuPrefersDraw_DrawPreference);
     }
 
     return true;
 }
 
 bool GrGLGpu::onWritePixels(GrSurface* surface,
                             int left, int top, int width, int height,
                             GrPixelConfig config, const void* buffer,
                             size_t rowBytes) {
-    if (nullptr == buffer) {
-        return false;
-    }
-
     GrGLTexture* glTex = static_cast<GrGLTexture*>(surface->asTexture());
     if (!glTex) {
         return false;
     }
 
     // OpenGL doesn't do sRGB <-> linear conversions when reading and writing pixels.
     if (GrPixelConfigIsSRGB(surface->config()) != GrPixelConfigIsSRGB(config)) {
         return false;
     }
 
@@ skipping 2610 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }