Prevent guest views from issuing a search for empty text.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 1ee7a7dc3807794f0707f36abbef980e1c51da21..4401ff5d21a76f70d89dddf5155f11943257f6dc 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -2723,6 +2723,12 @@ bool WebContentsImpl::IsSubframe() const {
 void WebContentsImpl::Find(int request_id,
                            const base::string16& search_text,
                            const blink::WebFindOptions& options) {
+  // Cowardly refuse to search for no text.
+  if (search_text.empty()) {
+    NOTREACHED();

[Charlie Reis, 2015/09/28 19:35:17]

I take it there's some other code that returns early if you hit enter in an
empty Find box on a normal tab?

[Lei Zhang, 2015/09/28 20:01:51]

Yes, the normal find text box has a check.

+    return;
+  }
+
   // See if a top level browser plugin handles the find request first.
   if (browser_plugin_embedder_ &&
       browser_plugin_embedder_->Find(request_id, search_text, options)) {