Code: WebContents* TabsCaptureVisibleTabFunction::GetWebContentsForID(
    int window_id,
    std::string* error) {
  Browser* browser = NULL;
  if (!GetBrowserFromWindowID(chrome_details_, window_id, &browser, error))
    return nullptr;

  WebContents* contents = browser->tab_strip_model()->GetActiveWebContents();
  if (!contents) {
    *error = "No active web contents to capture";
    return nullptr;
   }
 
   if (!extension()->permissions_data()->CanCaptureVisiblePage(
           SessionTabHelper::IdForTab(contents).id(), error)) {
     return nullptr;
   }
  return contents;
}

Vulnerability Type: Bypass 
CWE ID: CWE-20
Summary: Insufficient policy enforcement in Extensions API in Google Chrome prior to 67.0.3396.62 allowed an attacker who convinced a user to install a malicious extension to bypass navigation restrictions via a crafted Chrome Extension.
Commit Message: [Extensions] Restrict tabs.captureVisibleTab()

Modify the permissions for tabs.captureVisibleTab(). Instead of just
checking for <all_urls> and assuming its safe, do the following:
- If the page is a "normal" web page (e.g., http/https), allow the
  capture if the extension has activeTab granted or <all_urls>.
- If the page is a file page (file:///), allow the capture if the
  extension has file access *and* either of the <all_urls> or
  activeTab permissions.
- If the page is a chrome:// page, allow the capture only if the
  extension has activeTab granted.

Bug: 810220

Change-Id: I1e2f71281e2f331d641ba0e435df10d66d721304
Reviewed-on: https://chromium-review.googlesource.com/981195
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548891}