Ensure GL initialization only happens once, and provide common init path

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.
 
 // This include must be here so that the includes provided transitively
 // by gl_surface_egl.h don't make it impossible to compile this code.
 #include "third_party/mesa/src/include/GL/osmesa.h"
 
 #include "ui/gl/gl_surface_egl.h"
 
@@ skipping 766 matching lines @@
 
 GLSurfaceOSMesaHeadless::GLSurfaceOSMesaHeadless(gfx::AcceleratedWidget window)
     : GLSurfaceOSMesa(OSMESA_BGRA, gfx::Size(1, 1)) {
   DCHECK(window);
 }
 
 GLSurfaceOSMesaHeadless::~GLSurfaceOSMesaHeadless() { Destroy(); }
 
 // static
 bool GLSurface::InitializeOneOffInternal() {
-  if (GetGLImplementation() == kGLImplementationOSMesaGL) {
-    return true;
-  }
-  DCHECK(GetGLImplementation() == kGLImplementationEGLGLES2);
-
-  if (!GLSurfaceEGL::InitializeOneOff()) {
-    LOG(ERROR) << "GLSurfaceEGL::InitializeOneOff failed.";
-    return false;
+  switch (GetGLImplementation()) {
+    case kGLImplementationEGLGLES2:
+      if (!GLSurfaceEGL::InitializeOneOff()) {
+        LOG(ERROR) << "GLSurfaceEGL::InitializeOneOff failed.";
+        return false;
+      }
+    default:
+      break;
   }
   return true;
 }
 
 // static
 scoped_refptr<GLSurface>
 GLSurface::CreateViewGLSurface(gfx::AcceleratedWidget window) {
 
   if (GetGLImplementation() == kGLImplementationOSMesaGL) {
     scoped_refptr<GLSurface> surface(new GLSurfaceOSMesaHeadless(window));
@@ skipping 47 matching lines @@
     }
     default:
       NOTREACHED();
       return NULL;
   }
 }
 
 #endif
 
 }  // namespace gfx