Prevent guest views from issuing a search for empty text.

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index 08c5ba9b8f2f01c84cede287381a1c8f718d165b..b5bafa7c9556aefca75e0178ebaf204f7ecabeb2 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -642,7 +642,7 @@ class WebContents : public PageNavigator,
   // removed since we can then embed iframes in different processes.
   virtual bool IsSubframe() const = 0;
 
-  // Finds text on a page.
+  // Finds text on a page. |search_text| should not be empty.
   virtual void Find(int request_id,
                     const base::string16& search_text,
                     const blink::WebFindOptions& options) = 0;