[MD Feedback] Add basic chrome://feedback dialog.

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
+
+MdFeedbackDialogController::MdFeedbackDialogController() {}
+
+MdFeedbackDialogController::~MdFeedbackDialogController() {}
+
+// static
+MdFeedbackDialogController* MdFeedbackDialogController::GetOrCreate() {

[imcheng, 2016/06/02 04:19:10]

For now I do not see a need for the MdFeedbackDialogController class. I find
controller class to be appropriate when you need to access/manipulate the dialog
from the browser side in addition to the WebUI side. Consider removing this
class for now and turning MdFeedbackDialogController::Show into a nonmember
function.

[apacible, 2016/06/02 18:04:20]

Per offline conversation:
- Removed MdFeedbackDialogController.
- Moved MdFeedbackDialogDelegate to MdFeedbackUI.
- Moved Show to MdFeedbackUI and renamed it.

+  // TODO(apacible): If there is already an existing controller for the browser
+  // profile, reuse it.
+  return new MdFeedbackDialogController();
+}
+
+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(NULL, browser_context, new MdFeedbackDialogDelegate());

[imcheng, 2016/06/02 04:19:10]

Is the intention that at most one feedback UI dialog can be opened at a time,
and does chrome::ShowWebDialog already provide that behavior?

[apacible, 2016/06/02 18:04:20]

Correct, at most one feedback UI dialog can be opened at a time, per profile. If
you had multiple Chrome profiles up, you could open the dialog once per profile.

ShowWebDialog does not provide this behavior. I'm also discussing some options
for the Mac dialog (so this may change down the line) with the mac dev team.
This is mostly an unblocker for starting the WebUI work, which should not be
affected by the native dialog changes.

+#endif
+}