Prevent guest views from issuing a search for empty text.

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 2705 matching lines @@
   return download_id;
 }
 
 bool WebContentsImpl::IsSubframe() const {
   return is_subframe_;
 }
 
 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)) {
     return;
   }
   Send(new ViewMsg_Find(GetRoutingID(), request_id, search_text, options));
 }
 
 void WebContentsImpl::StopFinding(StopFindAction action) {
   // See if a top level browser plugin handles the stop finding request first.
@@ skipping 1905 matching lines @@
   return NULL;
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content