Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/browser/instant/instant_controller.cc

Index: chrome/browser/instant/instant_controller.cc
diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index 99e35ead1a1b70cb1c372ab744f3f3da5cda42a4..01ed2142fed49c955fcceba3fcbfbe3a9e79e92b 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -667,6 +667,11 @@ void InstantController::ShowInstantPreview(InstantLoader* loader,
     Show(reason, height, units);
 }
 
+void InstantController::StartCapturingKeyStrokes(InstantLoader* loader) {
+  if (loader_ == loader && extended_enabled_ && model_.mode().is_ntp())
+    browser_->SetInvisibleFocus();
+}
+
 void InstantController::InstantSupportDetermined(InstantLoader* loader,
                                                  bool supports_instant) {
   if (supports_instant) {