Support multiple null GL contexts on a thread.

src/gpu/gl/SkNullGLContext.h

Index: src/gpu/gl/SkNullGLContext.h
diff --git a/src/gpu/gl/SkNullGLContext.h b/src/gpu/gl/SkNullGLContext.h
deleted file mode 100644
index b0432ba2e64c36d32b5f9f0ccc365d791037bf22..0000000000000000000000000000000000000000
--- a/src/gpu/gl/SkNullGLContext.h
+++ /dev/null
@@ -1,35 +0,0 @@
-
-/*
- * 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 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;
-    }
-
-private:
-    SkNullGLContext();
-};
-
-#endif