Add common GLFence::IsSupported() check

gpu/command_buffer/service/mailbox_synchronizer.cc

Index: gpu/command_buffer/service/mailbox_synchronizer.cc
diff --git a/gpu/command_buffer/service/mailbox_synchronizer.cc b/gpu/command_buffer/service/mailbox_synchronizer.cc
index d25368ab09642ce0485747a7f314f02174ba24fe..59a3884bcc16e17fcc975ab9ede3c458ca2d2932 100644
--- a/gpu/command_buffer/service/mailbox_synchronizer.cc
+++ b/gpu/command_buffer/service/mailbox_synchronizer.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "gpu/command_buffer/service/mailbox_manager.h"
 #include "gpu/command_buffer/service/texture_manager.h"
+#include "ui/gl/gl_fence.h"
 #include "ui/gl/gl_implementation.h"
 
 namespace gpu {
@@ -32,7 +33,7 @@ bool MailboxSynchronizer::Initialize() {
         if (!gfx::g_driver_egl.ext.b_EGL_KHR_image_base ||
             !gfx::g_driver_egl.ext.b_EGL_KHR_gl_texture_2D_image ||
             !gfx::g_driver_gl.ext.b_GL_OES_EGL_image ||
-            !gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync) {
+            !gfx::GLFence::IsSupported()) {
           LOG(WARNING) << "MailboxSync not supported due to missing EGL "
                           "image/fence support";
           return false;