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

ui/gl/gl_surface_egl.cc

Index: ui/gl/gl_surface_egl.cc
diff --git a/ui/gl/gl_surface_egl.cc b/ui/gl/gl_surface_egl.cc
index 7c36984843a7eadbf12da2bf7c3ec969542a492e..705cd1a0e982fc36803d8c4bac433c9911adbcb4 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -35,6 +35,10 @@ extern "C" {
 #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
@@ -288,6 +292,20 @@ bool GLSurfaceEGL::InitializeOneOff() {
   const EGLint* config_attribs = ui::OzonePlatform::GetInstance()
                                      ->GetSurfaceFactoryOzone()
                                      ->GetEGLSurfaceProperties(kConfigAttribs);
+#elif defined(USE_X11) && !defined(OS_CHROMEOS)
+  const EGLint* config_attribs = kConfigAttribs;
+
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableTransparentVisuals)) {
+    const int kBufferSizeOffset = 1;
+    const int kAlphaSizeOffset = 3;
+    EGLint* config_non_const = const_cast<EGLint*>(kConfigAttribs);

[hendrikw, 2015/11/11 23:55:46]

Not a big fan of this const stuff.

How about above the declaration of kConfigAttribs you do something like:

  EGLint buffer_size = 32;
  EGLint alpha_size = 8;

#if defined(USE_X11) && !defined(OS_CHROMEOS)
  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(...) {
    buffer_size = 24;
    alpha_size = 0;
  }
#endif

And then use those vars in the declaration of kConfigAttribs?

[Julien Isorce Samsung, 2015/11/12 11:06:48]

Much easier to read indeed, thx. I addressed remarks and uploaded "Patch Set 4".

+
+    config_non_const[kBufferSizeOffset] = 24;
+    config_non_const[kAlphaSizeOffset] = 0;
+
+    config_attribs = config_non_const;
+  }
 #else
   const EGLint* config_attribs = kConfigAttribs;
 #endif