Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/browser/ui/omnibox/omnibox_edit_model.cc

Index: chrome/browser/ui/omnibox/omnibox_edit_model.cc
diff --git a/chrome/browser/ui/omnibox/omnibox_edit_model.cc b/chrome/browser/ui/omnibox/omnibox_edit_model.cc
index a643b741f48e4bc489b1209229f0d42b350a248c..503ae2eecd2df6f28e76709970bbb596df11a74b 100644
--- a/chrome/browser/ui/omnibox/omnibox_edit_model.cc
+++ b/chrome/browser/ui/omnibox/omnibox_edit_model.cc
@@ -725,6 +725,11 @@ void OmniboxEditModel::OnSetFocus(bool control_down) {
   NotifySearchTabHelper();
 }
 
+void OmniboxEditModel::OnFocusVisibilityChange(bool is_focus_visible) {
+  is_focus_visible_ = is_focus_visible;

[dhollowa, 2012/11/20 23:50:17]

Question: is there an invariant here that is_focus_visible_ == true implies
has_focus_ == true?  I.e. should we force it?  Or will other code be responsible
for setting has_focus_, therefore a DCHECK here?

[samarth, 2012/11/21 00:40:15]

My preference was to completely decouple focus "visibility" from whether the box
actually has focus.  Or in other words, it shouldn't matter which order you set
these in--the end result would be the same.  Tying the two together can be
tricky because plenty of things rely on focus and plenty of low-level components
can give or take focus away.

I tried to clarify this in the comments for is_focus_visible_ in
omnibox_edit_model.h.  Let me know if it's still unclear of if you prefer
different semantics.

[dhollowa, 2012/11/21 00:55:19]

That's fine if we can get away with it.  Thanks for the clarification.

+  // TODO(samarth): communicate this state to InstantController.
+}
+
 void OmniboxEditModel::OnWillKillFocus(gfx::NativeView view_gaining_focus) {
   SetInstantSuggestion(InstantSuggestion());
 
@@ -738,6 +743,7 @@ void OmniboxEditModel::OnWillKillFocus(gfx::NativeView view_gaining_focus) {
 
 void OmniboxEditModel::OnKillFocus() {
   has_focus_ = false;
+  is_focus_visible_ = false;
   control_key_state_ = UP;
   paste_state_ = NONE;
 }