Enable creation of offscreen contexts which own their backing surface.

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 0bce1d00911a2be32ed9ca1f70446fe8468112c5..a8b0efb966a297798d5fb931fa564ab4beaf19cf 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -241,6 +241,15 @@ EGLConfig ChooseConfig(GLSurface::Format format) {
 
   EGLint buffer_size = 32;
   EGLint alpha_size = 8;
+  EGLint depth_size = EGL_DONT_CARE;
+
+  if (format == GLSurface::SURFACE_ARGB8888_DEPTH24) {
+    depth_size = 24;
+    format = GLSurface::SURFACE_ARGB8888;
+  } else if (format == GLSurface::SURFACE_RGB565_DEPTH24) {
+    depth_size = 24;
+    format = GLSurface::SURFACE_RGB565;
+  }
 
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
   ui::XVisualManager::GetInstance()->ChooseVisualForWindow(
@@ -263,6 +272,8 @@ EGLConfig ChooseConfig(GLSurface::Format format) {
                                     8,
                                     EGL_RED_SIZE,
                                     8,
+                                    EGL_DEPTH_SIZE,
+                                    depth_size,
                                     EGL_RENDERABLE_TYPE,
                                     renderable_type,
                                     EGL_SURFACE_TYPE,
@@ -277,6 +288,8 @@ EGLConfig ChooseConfig(GLSurface::Format format) {
                                    6,
                                    EGL_RED_SIZE,
                                    5,
+                                   EGL_DEPTH_SIZE,
+                                   depth_size,
                                    EGL_RENDERABLE_TYPE,
                                    renderable_type,
                                    EGL_SURFACE_TYPE,