Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/browser/instant/instant_controller.h

Index: chrome/browser/instant/instant_controller.h
diff --git a/chrome/browser/instant/instant_controller.h b/chrome/browser/instant/instant_controller.h
index 941dd15b96190124a9b9567ab4e62828fa91f030..34e78ab1e86101103bbee3e637b643aefa4cef20 100644
--- a/chrome/browser/instant/instant_controller.h
+++ b/chrome/browser/instant/instant_controller.h
@@ -130,6 +130,10 @@ class InstantController {
                           int height,
                           InstantSizeUnits units);
 
+  // Invoked by InstantLoader to request the browser to start capturing user key
+  // strokes.
+  void StartCapturingKeyStrokes();
+
   // Invoked by InstantLoader when it has swapped a different WebContents into
   // the preview, usually because a prerendered page was navigated to.
   void SwappedWebContents();