Allow Widget to pass accelerator handling to its parent.

ui/views/widget/widget_accelerator_handling_delegate.cc

+// Copyright (c) 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/views/widget/widget_accelerator_handling_delegate.h"
+
+#include "ui/views/focus/focus_manager_delegate.h"
+#include "ui/views/widget/widget.h"
+
+namespace views {
+
+namespace {
+
+class ForwardingFocusManagerDelegate : public FocusManagerDelegate {
+ public:
+  explicit ForwardingFocusManagerDelegate(
+      WidgetAcceleratorHandlingDelegate* owner)
+      : owner_(owner->GetWeakPtr()) {}
+  ~ForwardingFocusManagerDelegate() override = default;
+
+  // Implements FocusManagerDelegate:
+  bool ProcessAccelerator(const ui::Accelerator& accelerator) override {
+    if (!owner_)
+      return false;
+    Widget* target = owner_->accelerator_target();
+    if (!target)
+      return false;
+    FocusManager* target_focus_manager = target->GetFocusManager();
+    if (!target_focus_manager)
+      return false;
+    return target_focus_manager->ProcessAccelerator(accelerator);
+  }
+
+ private:
+  base::WeakPtr<WidgetAcceleratorHandlingDelegate> owner_;
+
+  DISALLOW_COPY_AND_ASSIGN(ForwardingFocusManagerDelegate);
+};
+
+}  // namespace
+
+WidgetAcceleratorHandlingDelegate::WidgetAcceleratorHandlingDelegate(
+    Widget* accelerator_target)
+    : accelerator_target_(accelerator_target),
+      accelerator_target_observer_(this),
+      weak_factory_(this) {
+  DCHECK(accelerator_target_);
+  accelerator_target_observer_.Add(accelerator_target_);
+  accelerator_target_->AddHandleAcceleratorsOverride();
+}
+
+WidgetAcceleratorHandlingDelegate::~WidgetAcceleratorHandlingDelegate() {
+  accelerator_target_->RemoveHandleAcceleratorsOverride();
+}
+
+base::WeakPtr<WidgetAcceleratorHandlingDelegate>
+WidgetAcceleratorHandlingDelegate::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
+}
+
+std::unique_ptr<FocusManagerDelegate>
+WidgetAcceleratorHandlingDelegate::CreateFocusManagerDelegate() {
+  return base::MakeUnique<ForwardingFocusManagerDelegate>(this);
+}
+
+void WidgetAcceleratorHandlingDelegate::OnWidgetDestroying(Widget* widget) {
+  DCHECK_EQ(accelerator_target_, widget);
+  accelerator_target_ = nullptr;
+  accelerator_target_observer_.Remove(widget);
+}
+
+}  // namespace views