Support multiple null GL contexts on a thread.

include/gpu/gl/SkNullGLContext.h

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkNullGLContext_DEFINED
 #define SkNullGLContext_DEFINED
 
 #include "gl/SkGLContext.h"
 
 class SK_API SkNullGLContext : public SkGLContext {
 public:
     ~SkNullGLContext() SK_OVERRIDE;
-    void makeCurrent() const SK_OVERRIDE {};
+    void makeCurrent() const SK_OVERRIDE;
     void swapBuffers() const SK_OVERRIDE {};
 
-    static SkNullGLContext* Create(GrGLStandard forcedGpuAPI) {
-        if (kGLES_GrGLStandard == forcedGpuAPI) {
-            return NULL;
-        }
-        SkNullGLContext* ctx = SkNEW(SkNullGLContext);
-        if (!ctx->isValid()) {
-            SkDELETE(ctx);
-            return NULL;
-        }
-        return ctx;
-    }
+    static SkNullGLContext* Create(GrGLStandard);
+
+    struct ContextState;
 
 private:
     SkNullGLContext();
+
+    ContextState* fState;
 };
 
 #endif