command_buffer: Implement CHROMIUM_framebuffer_mixed_samples extension

ui/gl/gl_bindings.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GL_GL_BINDINGS_H_
 #define UI_GL_GL_BINDINGS_H_
 
 #include <string>
 
 // Includes the platform independent and platform dependent GL headers.
@@ skipping 255 matching lines @@
 #define GL_PATH_STENCIL_REF_CHROMIUM 0x90B8
 #define GL_PATH_STENCIL_VALUE_MASK_CHROMIUM 0x90B9
 #endif
 
 #ifndef GL_EXT_multisample_compatibility
 #define GL_EXT_multisample_compatibility 1
 #define GL_MULTISAMPLE_EXT 0x809D
 #define GL_SAMPLE_ALPHA_TO_ONE_EXT 0x809F
 #endif /* GL_EXT_multisample_compatibility */
 
+#ifndef GL_CHROMIUM_framebuffer_mixed_samples
+#define GL_CHROMIUM_framebuffer_mixed_samples 1
+#define GL_COVERAGE_MODULATION_CHROMIUM 0x9332
+#endif /* GL_CHROMIUM_framebuffer_mixed_samples */
+
 #ifndef GL_KHR_blend_equation_advanced
 #define GL_KHR_blend_equation_advanced 1
 #define GL_COLORBURN_KHR                  0x929A
 #define GL_COLORDODGE_KHR                 0x9299
 #define GL_DARKEN_KHR                     0x9297
 #define GL_DIFFERENCE_KHR                 0x929E
 #define GL_EXCLUSION_KHR                  0x92A0
 #define GL_HARDLIGHT_KHR                  0x929B
 #define GL_HSL_COLOR_KHR                  0x92AF
 #define GL_HSL_HUE_KHR                    0x92AD
@@ skipping 209 matching lines @@
 #elif defined(OS_ANDROID)
 
 GL_EXPORT extern EGLApi* g_current_egl_context;
 GL_EXPORT extern DriverEGL g_driver_egl;
 
 #endif
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_BINDINGS_H_