gl_surface_egl: ensure off and on screen surfaces use the same EGLConfig

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"
 
 #if defined(OS_ANDROID)
 #include <android/native_window_jni.h>
 #endif
 
@@ skipping 17 matching lines @@
 extern "C" {
 #include <X11/Xlib.h>
 }
 #endif
 
 #if defined (USE_OZONE)
 #include "ui/ozone/public/ozone_platform.h"
 #include "ui/ozone/public/surface_factory_ozone.h"
 #endif
 
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+#include "ui/gfx/x/x11_switches.h"
+#endif
+
 #if !defined(EGL_FIXED_SIZE_ANGLE)
 #define EGL_FIXED_SIZE_ANGLE 0x3201
 #endif
 
 #if !defined(EGL_OPENGL_ES3_BIT)
 #define EGL_OPENGL_ES3_BIT 0x00000040
 #endif
 
 // From ANGLE's egl/eglext.h.
 
@@ skipping 218 matching lines @@
   if (g_display == EGL_NO_DISPLAY)
     return false;
 
   // Choose an EGL configuration.
   // On X this is only used for PBuffer surfaces.
   EGLint renderable_type = EGL_OPENGL_ES2_BIT;
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableUnsafeES3APIs)) {
     renderable_type = EGL_OPENGL_ES3_BIT;
   }
+
+  EGLint buffer_size = 32;
+  EGLint alpha_size = 8;
+
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableTransparentVisuals)) {

[piman, 2015/11/17 20:53:52]

I would prefer if we didn't rely on behavior of the browser side relative to
this flag ("if that flag is set, then the browser must have created windows with
32 bit visuals otherwise it must be 24 bits"). I think we should solve the
problem the same way we solved it for GLX, i.e. by using an unmapped window
rather than a pbuffer, and getting a config that's compatible with it.

In the long run, I think what we really need to do is pick a visual in the
browser (early enough), pass that to the GPU process, and pick a config out of
that.

+    buffer_size = 24;
+    alpha_size = 0;
+  }
+#endif
+
   const EGLint kConfigAttribs[] = {
-    EGL_BUFFER_SIZE, 32,
-    EGL_ALPHA_SIZE, 8,
+    EGL_BUFFER_SIZE, buffer_size,
+    EGL_ALPHA_SIZE, alpha_size,
     EGL_BLUE_SIZE, 8,
     EGL_GREEN_SIZE, 8,
     EGL_RED_SIZE, 8,
     EGL_RENDERABLE_TYPE, renderable_type,
     EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
     EGL_NONE
   };
 
 #if defined(USE_OZONE)
   const EGLint* config_attribs = ui::OzonePlatform::GetInstance()
@@ skipping 625 matching lines @@
 }
 
 void* SurfacelessEGL::GetShareHandle() {
   return NULL;
 }
 
 SurfacelessEGL::~SurfacelessEGL() {
 }
 
 }  // namespace gfx