MacViews: Initial skeleton for implementing NativeWidgetMac

ui/views/cocoa/bridged_native_widget.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.
+
+#import "ui/views/cocoa/bridged_native_widget.h"
+
+#include "base/logging.h"
+#import "ui/views/cocoa/bridged_content_view.h"
+
+namespace views {
+
+BridgedNativeWidget::BridgedNativeWidget() {
+}
+
+BridgedNativeWidget::~BridgedNativeWidget() {
+  SetRootView(NULL);
+}
+
+void BridgedNativeWidget::Init(base::scoped_nsobject<NSWindow> window) {
+  DCHECK(!window_);
+  window_.swap(window);
+}
+
+void BridgedNativeWidget::SetRootView(views::View* view) {
+  if (view == [bridged_view_ hostedView])
+    return;
+
+  [bridged_view_ clearView];
+  bridged_view_.reset();
+  // Note that there can still be references to the old |bridged_view_|
+  // floating around in Cocoa libraries at this point. However, references to
+  // the old views::View will be gone, so any method calls will become no-ops.
+
+  if (view) {
+    bridged_view_.reset([[BridgedContentView alloc] initWithView:view]);
+    // Objective C initializers can return nil. However, if |view| is non-NULL
+    // this should be treated as an error and caught early.
+    CHECK(bridged_view_);
+  }
+  [window_ setContentView:bridged_view_];
+}
+
+}  // namespace views