Simplify HomeCardGestureManager::UpdateScrollState()

athena/home/home_card_gesture_manager.h

Index: athena/home/home_card_gesture_manager.h
diff --git a/athena/home/home_card_gesture_manager.h b/athena/home/home_card_gesture_manager.h
index 8749b91d8cb426be204f5b5822c9e46283603e47..e8f48d72e16b23026f2b37f8a7698b68d7001243 100644
--- a/athena/home/home_card_gesture_manager.h
+++ b/athena/home/home_card_gesture_manager.h
@@ -24,13 +24,13 @@ class ATHENA_EXPORT HomeCardGestureManager {
     // end up with |final_state|.
     virtual void OnGestureEnded(HomeCard::State final_state) = 0;
 
-    // Called when the gesture position is updated so that |delegate| should
-    // update the visual. The arguments represent the state of the current
-    // gesture position is switching from |from_state| to |to_state|, and
-    // the level of the progress is at |progress|, which is 0 to 1.
-    // |from_state| and |to_state| could be same. For example, if the user moves
-    // the finger down to the bottom of the screen, both states are MINIMIZED.
-    // In that case |progress| is 0.
+    // Called when the gesture position is updated so that |delegate| updates
+    // the visual. The arguments indicate that the gesture is switching from
+    // |from_state| to |to_state|, and that the level of progress is at
+    // |progress|, which is 0 to 1.
+    // |from_state| may be equal to |to_state| but only if

[Jun Mukai, 2014/09/02 03:51:42]

I think from_state could be equal to to_state and CENTERED when the user drag-up
from CENTERED state.

[pkotwicz, 2014/09/02 04:41:32]

With the current implementation of UpdateScrollState(), it does not seem
possible for both |from_state| and |to_state| to be CENTERED. Note line 97 in
home_card_gesture_manager.cc
VISIBLE_MINIMIZED > VISIBLE_BOTTOM > VISIBLE_CENTERED > HIDDEN

+    // |from_state| == VISIBLE_MINIMIZED. This occurs if the user moves their
+    // finger to the bottom of the screen.
     virtual void OnGestureProgressed(
         HomeCard::State from_state,
         HomeCard::State to_state,