Refactor GL surface format handling

ui/gl/init/gl_factory_x11.cc

 // Copyright 2016 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/init/gl_factory.h"
 
 #include "base/trace_event/trace_event.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_context_egl.h"
 #include "ui/gl/gl_context_glx.h"
@@ skipping 67 matching lines @@
       DCHECK(window != gfx::kNullAcceleratedWidget);
       return InitializeGLSurface(new NativeViewGLSurfaceEGLX11(window));
     case kGLImplementationMockGL:
       return new GLSurfaceStub;
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
-scoped_refptr<GLSurface> CreateOffscreenGLSurface(const gfx::Size& size) {
+scoped_refptr<GLSurface> CreateOffscreenGLSurfaceWithFormat(
+    const gfx::Size& size, GLSurfaceFormat format) {
   TRACE_EVENT0("gpu", "gl::init::CreateOffscreenGLSurface");
   switch (GetGLImplementation()) {
     case kGLImplementationOSMesaGL:
-      return InitializeGLSurface(
-          new GLSurfaceOSMesa(GLSurface::SURFACE_OSMESA_RGBA, size));
+      if (format.IsDefault()) {
+        format = GLSurfaceFormat(GLSurfaceFormat::SURFACE_OSMESA_RGBA);
+      }
+      return InitializeGLSurfaceWithFormat(
+          new GLSurfaceOSMesa(format, size), format);
     case kGLImplementationDesktopGL:
-      return InitializeGLSurface(new UnmappedNativeViewGLSurfaceGLX(size));
+      return InitializeGLSurfaceWithFormat(
+          new UnmappedNativeViewGLSurfaceGLX(size), format);
     case kGLImplementationEGLGLES2:
-      return InitializeGLSurface(new PbufferGLSurfaceEGL(size));
+      return InitializeGLSurfaceWithFormat(
+          new PbufferGLSurfaceEGL(size), format);
     case kGLImplementationMockGL:
       return new GLSurfaceStub;
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 }  // namespace init
 }  // namespace gl