command_buffer_gles2: Implement EGL default Display as a global object

gpu/gles2_conform_support/egl/test_support.h

 // Copyright (c) 2016 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 GPU_GLES2_CONFORM_SUPPORT_EGL_TEST_SUPPORT_H_
 #define GPU_GLES2_CONFORM_SUPPORT_EGL_TEST_SUPPORT_H_
 
+#include <EGL/egl.h>
+
 #if defined(COMPONENT_BUILD) && defined(COMMAND_BUFFER_GLES_LIB_SUPPORT_ONLY)
 // A variable used for communicating whether the app has initialized the global
 // variables.
 // On component build, the dynamic library and the Chromium test
 // runner executable refer to the same global variables. Any non-Chromium client
 // of the dynamic library will not initialize the globabl variables.
 // On non-component (static) build, the library and the runner have distinct
 // global variables.
 EGLAPI extern EGLAPIENTRY bool g_command_buffer_gles_has_atexit_manager;
 #endif
 
+extern "C" {
+// A function to support GTF windowless tests. gles2_conform_test_windowless and
+// khronos_glcts_test_windowless create "windowless" native windows and render
+// to those. The test runners do not at the moment implement creating said
+// windowless native windows. This call sets the system so that it will create a
+// pbuffer when eglCreateWindow is called.
+EGLAPI EGLAPIENTRY void
+CommandBufferGLESSetNextCreateWindowSurfaceCreatesPBuffer(EGLDisplay eglDisplay,
+                                                          EGLint width,
+                                                          EGLint height);
+}
 #endif