[MD Feedback] Add placeholder feedback entry point.

chrome/browser/ui/webui/md_feedback/md_feedback_dialog_controller.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 "chrome/browser/ui/webui/md_feedback/md_feedback_dialog_controller.h"
+
+#include "chrome/browser/ui/browser_dialogs.h"
+#include "chrome/common/url_constants.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/web_contents.h"
+#include "ui/web_dialogs/web_dialog_delegate.h"
+#include "url/gurl.h"
+
+namespace {
+
+// The WebDialogDelegate that specifies what the MD Feedback dialog will look
+// like.
+class MdFeedbackDialogDelegate : public ui::WebDialogDelegate {
+ public:
+  MdFeedbackDialogDelegate() {}
+  ~MdFeedbackDialogDelegate() override {}
+
+  ui::ModalType GetDialogModalType() const override {
+    return ui::MODAL_TYPE_SYSTEM;
+  }
+
+  base::string16 GetDialogTitle() const override {
+    return base::string16();
+  }
+
+  GURL GetDialogContentURL() const override {
+    return GURL(chrome::kChromeUIFeedbackURL);
+  }
+
+  void GetWebUIMessageHandlers(
+      std::vector<content::WebUIMessageHandler*>* handlers) const override {}
+
+  void GetDialogSize(gfx::Size* size) const override {
+    // TODO(apacible): Update when WebUI sizing behavior is finalized.
+    size->SetSize(400, 600);
+  }
+
+  std::string GetDialogArgs() const override {
+    return std::string();
+  }
+
+  void OnDialogClosed(const std::string& json_retval) override {
+    delete this;
+  }
+
+  void OnCloseContents(
+      content::WebContents* source, bool* out_close_dialog) override {}
+
+  bool ShouldShowDialogTitle() const override {
+    return false;
+  }
+
+  bool HandleContextMenu(const content::ContextMenuParams& params) override {
+    // Do not show the contextual menu.
+    return true;
+  }
+};
+
+}  // namespace
+
+// static
+MdFeedbackDialogController* MdFeedbackDialogController::GetInstance() {
+  return base::Singleton<MdFeedbackDialogController>::get();
+}
+
+void MdFeedbackDialogController::Show(
+    content::BrowserContext* browser_context) {
+  // TODO(apacible): Platform dependent implementations.
+#if !defined(OS_MACOSX)
+  // TODO(apacible): If a feedback dialog is already open, bring that dialog
+  // to the front rather than creating a new dialog.
+  chrome::ShowWebDialog(nullptr, browser_context,
+      new MdFeedbackDialogDelegate());
+#endif  // !defined(OS_MACOSX)
+}
+
+MdFeedbackDialogController::MdFeedbackDialogController() {}