Reduce GPU mailbox size to 16 bytes

gpu/GLES2/gl2extchromium.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.
 
 // This file contains Chromium-specific GLES2 extensions declarations.
 
 #ifndef GPU_GLES2_GL2EXTCHROMIUM_H_
 #define GPU_GLES2_GL2EXTCHROMIUM_H_
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /* GL_CHROMIUM_texture_mailbox */
 #ifndef GL_CHROMIUM_texture_mailbox
 #define GL_CHROMIUM_texture_mailbox 1
 
 #ifndef GL_MAILBOX_SIZE_CHROMIUM
-#define GL_MAILBOX_SIZE_CHROMIUM 64
+#define GL_MAILBOX_SIZE_CHROMIUM 16

[dcheng, 2016/10/29 00:32:23]

Unrelated, but we could probably make this a constexpr not-macro thing now.

 #endif
 #ifdef GL_GLEXT_PROTOTYPES
 GL_APICALL void GL_APIENTRY glGenMailboxCHROMIUM(GLbyte* mailbox);
 GL_APICALL void GL_APIENTRY glProduceTextureCHROMIUM(
     GLenum target, const GLbyte* mailbox);
 GL_APICALL void GL_APIENTRY glProduceTextureDirectCHROMIUM(
     GLuint texture, GLenum target, const GLbyte* mailbox);
 GL_APICALL void GL_APIENTRY glConsumeTextureCHROMIUM(
     GLenum target, const GLbyte* mailbox);
 GL_APICALL GLuint GL_APIENTRY glCreateAndConsumeTextureCHROMIUM(
@@ skipping 1168 matching lines @@
 GL_APICALL void GL_APIENTRY glCoverageModulationCHROMIUM(GLenum components);
 #endif
 #define GL_COVERAGE_MODULATION_CHROMIUM 0x9332
 #endif /* GL_CHROMIUM_framebuffer_mixed_samples */
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif  // GPU_GLES2_GL2EXTCHROMIUM_H_