Have GMs read the GrContext via a setter/getter rather than a global.

gm/gm.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 "gm.h"
 using namespace skiagm;
 
 SkString GM::gResourcePath;
 
 GM::GM() {
     fBGColor = SK_ColorWHITE;
     fCanvasIsDeferred = false;
     fHaveCalledOnceBeforeDraw = false;
+#if SK_SUPPORT_GPU
+    fGr = NULL;
+#endif
 }
 GM::~GM() {}
 
 void GM::draw(SkCanvas* canvas) {
     this->drawBackground(canvas);
     this->drawContent(canvas);
 }
 
 void GM::drawContent(SkCanvas* canvas) {
     if (!fHaveCalledOnceBeforeDraw) {
@@ skipping 30 matching lines @@
     SkISize size = this->getISize();
     SkRect r = SkRect::MakeWH(SkIntToScalar(size.width()),
                               SkIntToScalar(size.height()));
     SkPaint paint;
     paint.setColor(color);
     canvas->drawRect(r, paint);
 }
 
 // need to explicitly declare this, or we get some weird infinite loop llist
 template GMRegistry* SkTRegistry<GM*(*)(void*)>::gHead;