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diff --git a/gfx/gl/ForceDiscreteGPUHelperCGL.h b/gfx/gl/ForceDiscreteGPUHelperCGL.h
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+++ b/gfx/gl/ForceDiscreteGPUHelperCGL.h
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+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ForceDiscreteGPUHelperCGL_h_
+#define ForceDiscreteGPUHelperCGL_h_
+
+#include <OpenGL/OpenGL.h>
+
+/** This RAII helper guarantees that we're on the discrete GPU during its
+ * lifetime.
+ *
+ * As long as any ForceDiscreteGPUHelperCGL object is alive, we're on the
+ * discrete GPU.
+ */
+class ForceDiscreteGPUHelperCGL {
+  CGLPixelFormatObj mPixelFormatObj;
+
+ public:
+  ForceDiscreteGPUHelperCGL() : mPixelFormatObj(nullptr) {
+    // the code in this function is taken from Chromium,
+    // src/ui/gfx/gl/gl_context_cgl.cc, r122013
+    // BSD-style license, (c) The Chromium Authors
+    CGLPixelFormatAttribute attribs[1];
+    attribs[0] = static_cast<CGLPixelFormatAttribute>(0);
+    GLint num_pixel_formats = 0;
+    CGLChoosePixelFormat(attribs, &mPixelFormatObj, &num_pixel_formats);
+  }
+
+  ~ForceDiscreteGPUHelperCGL() { CGLReleasePixelFormat(mPixelFormatObj); }
+};
+
+#endif  // ForceDiscreteGPUHelperCGL_h_