Remove unsafe cast from ImageTransportSurfaceOverlayMac::ScheduleCALayer.

ui/gl/gl_image_io_surface.mm

 // Copyright 2013 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_image_io_surface.h"
 
 #include <map>
 
 #include "base/callback_helpers.h"
 #include "base/mac/bind_objc_block.h"
@@ skipping 358 matching lines @@
 }
 
 base::ScopedCFTypeRef<IOSurfaceRef> GLImageIOSurface::io_surface() {
   return io_surface_;
 }
 
 base::ScopedCFTypeRef<CVPixelBufferRef> GLImageIOSurface::cv_pixel_buffer() {
   return cv_pixel_buffer_;
 }
 
+GLImage::Type GLImageIOSurface::GetType() const {
+  return Type::IOSURFACE;
+}
+
 // static
 unsigned GLImageIOSurface::GetInternalFormatForTesting(
     gfx::BufferFormat format) {
   DCHECK(ValidFormat(format));
   return TextureFormat(format);
 }
+
+// static
+GLImageIOSurface* GLImageIOSurface::FromGLImage(GLImage* image) {
+  if (!image || image->GetType() != Type::IOSURFACE)
+    return nullptr;
+  return static_cast<GLImageIOSurface*>(image);
+}
+
 }  // namespace gl