Code:  void CastCastView::ButtonPressed(views::Button* sender,
                                  const ui::Event& event) {
   DCHECK(sender == stop_button_);
  StopCast();
 }

Vulnerability Type: XSS 
CWE ID: CWE-79
Summary: Cross-site scripting (XSS) vulnerability in the DocumentLoader::maybeCreateArchive function in core/loader/DocumentLoader.cpp in Blink, as used in Google Chrome before 35.0.1916.114, allows remote attackers to inject arbitrary web script or HTML via crafted MHTML content, aka *Universal XSS (UXSS).*
Commit Message: Allow the cast tray to function as expected when the installed extension is missing API methods.

BUG=489445

Review URL: https://codereview.chromium.org/1145833003

Cr-Commit-Position: refs/heads/master@{#330663}