gpu: Add support for GLX_EXT_texture_from_pixmap extension.

third_party/khronos/GLES2/gl2ext.h

Index: third_party/khronos/GLES2/gl2ext.h
diff --git a/third_party/khronos/GLES2/gl2ext.h b/third_party/khronos/GLES2/gl2ext.h
index 3b162b8f492a327d6df6d0ee75ca6b129d77f2b3..45f60867ec57cf28bd7be8a4dc32c2ffe190bc71 100644
--- a/third_party/khronos/GLES2/gl2ext.h
+++ b/third_party/khronos/GLES2/gl2ext.h
@@ -2002,6 +2002,23 @@ typedef void (GL_APIENTRYP PFNGLCONSUMETEXTURECHROMIUM) (GLenum target, const  G
 #endif
 #endif
 
+/* GL_CHROMIUM_texture_from_pixmap */
+/* Exposes the GLX-specfic glXBindTexImageEXT entry point as a
+ * Chromium extension in the cross-platform API. Binds the Pixmap with
+ * the given ID (an X11 Pixmap) to the texture bound to the given target.
+ */
+#ifndef GL_CHROMIUM_texture_from_pixmap
+#define GL_CHROMIUM_texture_from_pixmap 1
+#ifdef GL_GLEXT_PROTOTYPES
+#define glTexImagePixmap2DCHROMIUM GLES2_GET_FUN(TexImagePixmap2DCHROMIUM)
+#if !defined(GLES2_USE_CPP_BINDINGS)
+GL_APICALL void GL_APIENTRY glTexImagePixmap2DCHROMIUM (GLenum target, GLuint pixmapId);
+#endif
+#else
+typedef void (GL_APIENTRYP PFNGLTEXIMAGEPIXMAP2DCHROMIUM) (GLenum target, GLuint pixmapId);
+#endif
+#endif
+
 #ifdef __cplusplus
 }
 #endif