gpu: Add GpuFence framework.

gpu/GLES2/gl2extchromium.h

Index: gpu/GLES2/gl2extchromium.h
diff --git a/gpu/GLES2/gl2extchromium.h b/gpu/GLES2/gl2extchromium.h
index 6ef50e2db254e12c36eb7b45492d747fc938456a..a808a572916a6a65a3bfe8c8f5780f237ece30e6 100644
--- a/gpu/GLES2/gl2extchromium.h
+++ b/gpu/GLES2/gl2extchromium.h
@@ -128,6 +128,20 @@ typedef GLuint(GL_APIENTRYP PFNGLCREATEGPUMEMORYBUFFERIMAGECHROMIUMPROC)(
     GLenum usage);
 #endif  /* GL_CHROMIUM_gpu_memory_buffer_image */
 
+/* GL_CHROMIUM_fence */
+#ifndef GL_CHROMIUM_fence
+#define GL_CHROMIUM_fence 1
+
+typedef struct _ClientFence* ClientFence;
+
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL GLuint GL_APIENTRY glCreateFenceCHROMIUM(ClientFence fence);
+GL_APICALL void GL_APIENTRY glDestroyFenceCHROMIUM(GLuint fence_id);
+#endif
+typedef GLuint(GL_APIENTRYP PFNGLCREATEFENCECHROMIUMPROC)(ClientFence fence);
+typedef void(GL_APIENTRYP PFNGLDESTROYFENCECHROMIUMPROC)(GLuint fence_id);
+#endif /* GL_CHROMIUM_fence */
+
 /* GL_CHROMIUM_deschedule */
 #ifndef GL_CHROMIUM_deschedule
 #define GL_CHROMIUM_deschedule 1