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}
void OmniboxViewViews::AppendDropFormats(
    int* formats,
    std::set<ui::Clipboard::FormatType>* format_types) {
  *formats = *formats | ui::OSExchangeData::URL;
}

void OmniboxViewViews::AppendDropFormats(
    int* formats,
    std::set<ui::Clipboard::FormatType>* format_types) {
  *formats = *formats | ui::OSExchangeData::URL;
}
