If the user selects text in the current tab, and types CTRL-F,...

chrome/browser/ui/find_bar/find_bar_controller.h

Index: chrome/browser/ui/find_bar/find_bar_controller.h
===================================================================
--- chrome/browser/ui/find_bar/find_bar_controller.h	(revision 71618)
+++ chrome/browser/ui/find_bar/find_bar_controller.h	(working copy)
@@ -8,6 +8,7 @@
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
+#include "base/string16.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
 
@@ -72,6 +73,14 @@
   // Mac.
   void MaybeSetPrepopulateText();
 
+  // For Windows and Linux this function sets the find text to the text that is
+  // selected in the current tab, if there is any such text. Mac has a global
+  // value for search, so this function does nothing on Mac.
+  void MaybeOverrideText();
+
+  // Gets the text that is selected in the current tab, or an empty string.
+  string16 GetSelectedText();
+
   NotificationRegistrar registrar_;
 
   scoped_ptr<FindBar> find_bar_;