Support header changeBounds transtion between fastlane and row

Now both fastlane and text view above row share the
same RowHeaderPresenter by default,  this allows
customized RowHeaderPresenter also being used in fast
lane.  Transition handles the transition between
them.

No longer detach/attach fast lane,  goes back to the
original hide/show mechanism, also split the transition
work from focusSearch() and performed after focus changed.

Added a Customized changeBounds transtion that support setting
staggered startDelay of fastlane text views.

Change-Id: I688074b850c088c2ff53039d235ba70f88c38da5
diff --git a/v17/leanback/res/values/dimens.xml b/v17/leanback/res/values/dimens.xml
index 21c5074..61792fa 100644
--- a/v17/leanback/res/values/dimens.xml
+++ b/v17/leanback/res/values/dimens.xml
@@ -29,9 +29,11 @@
     <dimen name="lb_browse_title_icon_margin_right">24dp</dimen>
     <dimen name="lb_browse_title_text_size">28sp</dimen>
 
-    <!-- 294 - 56 -->
+    <integer name="lb_browse_headers_transition_delay">250</integer>
+
     <integer name="lb_browse_rows_anim_duration">250</integer>
 
+    <dimen name="lb_browse_headers_vertical_margin">12dp</dimen>
     <dimen name="lb_browse_header_height">48dp</dimen>
     <dimen name="lb_browse_header_half_height">24dp</dimen>
     <dimen name="lb_browse_header_text_size">22sp</dimen>