Strip JavaScript schemas on Linux text drop

When dropping text onto the Omnibox, any leading JavaScript schemes
should be stripped to avoid a "self-XSS" attack. This stripping already
occurs in all cases except when plaintext is dropped on Linux. This CL
corrects that oversight.

Bug: 768910
Change-Id: I43af24ace4a13cf61d15a32eb9382dcdd498a062
Reviewed-on: https://chromium-review.googlesource.com/685638
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Eric Lawrence <elawrence@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504695}
bool OmniboxViewViews::IsCommandIdEnabled(int command_id) const {
  if (command_id == IDS_APP_PASTE)
    return !read_only() && !GetClipboardText().empty();
  if (command_id == IDS_PASTE_AND_GO)
    return !read_only() && model()->CanPasteAndGo(GetClipboardText());
  return Textfield::IsCommandIdEnabled(command_id) ||
         location_bar_view_->command_updater()->IsCommandEnabled(command_id);
}

bool OmniboxViewViews::IsCommandIdEnabled(int command_id) const {
  if (command_id == IDS_APP_PASTE)
    return !read_only() && !GetClipboardText().empty();
  if (command_id == IDS_PASTE_AND_GO)
    return !read_only() && model()->CanPasteAndGo(GetClipboardText());
  return Textfield::IsCommandIdEnabled(command_id) ||
         location_bar_view_->command_updater()->IsCommandEnabled(command_id);
}
