Make cross-process CALayers work on Mac

ui/base/cocoa/remote_layer_api.mm

+// Copyright 2014 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/base/cocoa/remote_layer_api.h"
+
+#include <objc/runtime.h>
+
+namespace ui {
+
+bool RemoteLayerAPISupported() {
+  // Verify the GPU process interfaces are present.
+  static Class caContextClass = NSClassFromString(@"CAContext");
+  if (!caContextClass)
+    return false;
+
+  // Note that because the contextId and layer properties are dynamic,
+  // instancesRespondToSelector will return NO for them.
+  static bool caContextClassValid =
+      [caContextClass respondsToSelector:
+          @selector(contextWithCGSConnection:options:)] &&
+      class_getProperty(caContextClass, "contextId") &&
+      class_getProperty(caContextClass, "layer");
+  if (!caContextClassValid)
+    return false;
+
+  // Verify the browser process interfaces are present.
+  static Class caLayerHostClass = NSClassFromString(@"CALayerHost");
+  if (!caLayerHostClass)
+    return false;
+
+  static bool caLayerHostClassValid =
+      [caLayerHostClass instancesRespondToSelector:@selector(contextId)] &&
+      [caLayerHostClass instancesRespondToSelector:@selector(setContextId:)];
+  if (!caLayerHostClassValid)
+    return false;
+
+  // If everything is there, we should be able to use the API.
+  return true;
+}
+
+}  // namespace
+