cros: Laser pointer fades out on release, do not cover palette.

ash/laser/laser_pointer_points.h

Index: ash/laser/laser_pointer_points.h
diff --git a/ash/laser/laser_pointer_points.h b/ash/laser/laser_pointer_points.h
index 19e95c1d1b3b1d6598cf47fb5483be7a9d153813..9b10bc0da1985ef7f8d20e07d9b1a927d48c2d28 100644
--- a/ash/laser/laser_pointer_points.h
+++ b/ash/laser/laser_pointer_points.h
@@ -23,7 +23,9 @@ class ASH_EXPORT LaserPointerPoints {
   // Struct to describe each point.
   struct LaserPoint {
     gfx::Point location;
-    base::Time creation_time;
+    // age is a value between [0,1] where 0 means the point was just added and 1
+    // means that the point is just about to be removed.
+    double age;

[jdufault, 2016/10/05 18:08:51]

Going from 0 -> 1 seems a bit strange to me (I'd expect 1 => new, 0 => old), but
with the name 'age' it works the 0 -> 1 works.

[sammiequon, 2016/10/05 21:15:22]

Is it normal convention to go the other way?

[jdufault, 2016/10/05 21:36:04]

I think so, but with 'age' it is confusing. ie, lifetime 1 => 0

   };
 
   // Constructor with a parameter to choose the fade out time of the points in
@@ -33,6 +35,10 @@ class ASH_EXPORT LaserPointerPoints {
 
   // Adds a point. Automatically clears points that are too old.
   void AddPoint(const gfx::Point& point);
+  // Updates the collection latest time. Automatically clears points that are
+  // too old.
+  void MoveForwardToCurrentTime();
+  void MoveForwardToTime(const base::Time& new_latest_time);
   // Removes all points.
   void Clear();
   // Gets the bounding box of the points.
@@ -55,6 +61,9 @@ class ASH_EXPORT LaserPointerPoints {
 
   base::TimeDelta life_duration_;
   std::deque<LaserPoint> points_;
+  // The latest time of the collection of points. This gets updated when new
+  // points are added or when MoveForwardInTime is called.
+  base::Time collection_latest_time_;
 
   DISALLOW_COPY_AND_ASSIGN(LaserPointerPoints);
 };