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

chrome/browser/ui/webui/md_feedback/md_feedback_ui.h

Index: chrome/browser/ui/webui/md_feedback/md_feedback_ui.h
diff --git a/chrome/browser/ui/webui/md_feedback/md_feedback_ui.h b/chrome/browser/ui/webui/md_feedback/md_feedback_ui.h
index f9d7d9e285ce7c6d346507eebe4b6e6b66ec5045..202a6edaae32f4feb09a4b269d830c470607dcf6 100644
--- a/chrome/browser/ui/webui/md_feedback/md_feedback_ui.h
+++ b/chrome/browser/ui/webui/md_feedback/md_feedback_ui.h
@@ -8,6 +8,10 @@
 #include "base/macros.h"
 #include "content/public/browser/web_ui_controller.h"
 
+namespace content {
+class BrowserContext;
+}  // namespace content
+
 // The WebUI for chrome://feedback.
 class MdFeedbackUI : public content::WebUIController {
  public:
@@ -17,4 +21,9 @@ class MdFeedbackUI : public content::WebUIController {
   DISALLOW_COPY_AND_ASSIGN(MdFeedbackUI);
 };
 
+// Create and show a web dialog with the MD feedback UI.
+// |browser_context| Is used to constructed the HTML dialog's WebContents.
+void ShowFeedbackWebDialog(
+    content::BrowserContext* browser_context);
+
 #endif  // CHROME_BROWSER_UI_WEBUI_MD_FEEDBACK_MD_FEEDBACK_UI_H_