X11: Use CopyFromParent colormap when possible (Reland)

ui/gl/gl_surface_egl.cc

 // 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.
 
 #include "ui/gl/gl_surface_egl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 131 matching lines @@
 
   if (warpDevice) {
     display_attribs.push_back(EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE);
     display_attribs.push_back(EGL_PLATFORM_ANGLE_DEVICE_TYPE_WARP_ANGLE);
   }
 
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
   Visual* visual;
   ui::XVisualManager::GetInstance()->ChooseVisualForWindow(
       true, &visual, nullptr, nullptr, nullptr);
+  if (visual == CopyFromParent)

[Corentin Wallez, 2016/11/03 21:16:56]

How about making XVisualManager only return CopyFromParent for the colormap?
Wouldn't that be sufficient for the purpose of this patch?

+    visual = DefaultVisual(g_display, DefaultScreen(g_display));
   display_attribs.push_back(EGL_X11_VISUAL_ID_ANGLE);
   display_attribs.push_back(static_cast<EGLint>(XVisualIDFromVisual(visual)));
 #endif
 
   display_attribs.push_back(EGL_NONE);
 
   return eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE,
                                   reinterpret_cast<void*>(native_display),
                                   &display_attribs[0]);
 }
@@ skipping 1038 matching lines @@
 }
 
 void* SurfacelessEGL::GetShareHandle() {
   return NULL;
 }
 
 SurfacelessEGL::~SurfacelessEGL() {
 }
 
 }  // namespace gl