ash: Add basic prediction code to the laser pointer.

ash/laser/laser_pointer_points.cc

Index: ash/laser/laser_pointer_points.cc
diff --git a/ash/laser/laser_pointer_points.cc b/ash/laser/laser_pointer_points.cc
index 2bd23cebd7ea83e4dfa5aafde61e27873ad9c824..1e597636b826d2542ea31e7d478c7f1415833323 100644
--- a/ash/laser/laser_pointer_points.cc
+++ b/ash/laser/laser_pointer_points.cc
@@ -16,15 +16,24 @@ LaserPointerPoints::LaserPointerPoints(base::TimeDelta life_duration)
 
 LaserPointerPoints::~LaserPointerPoints() {}
 
-void LaserPointerPoints::AddPoint(const gfx::PointF& point) {
-  MoveForwardToTime(base::Time::Now());
+void LaserPointerPoints::AddPoint(const gfx::PointF& point,
+                                  const base::TimeTicks& time) {
+  // Move forward in time if needed.
+  if (time > collection_latest_time_)
+    MoveForwardToTime(time);
 
   LaserPoint new_point;
   new_point.location = point;
+  new_point.time = time;
+  new_point.age = std::min((collection_latest_time_ - time).InMillisecondsF() /
+                               life_duration_.InMillisecondsF(),
+                           1.0);
   points_.push_back(new_point);
 }
 
-void LaserPointerPoints::MoveForwardToTime(const base::Time& latest_time) {
+void LaserPointerPoints::MoveForwardToTime(const base::TimeTicks& latest_time) {
+  DCHECK_GE(latest_time, collection_latest_time_);
+
   if (!points_.empty()) {
     DCHECK(!collection_latest_time_.is_null());
 
@@ -80,7 +89,7 @@ int LaserPointerPoints::GetNumberOfPoints() const {
 }
 
 const std::deque<LaserPointerPoints::LaserPoint>&
-LaserPointerPoints::laser_points() {
+LaserPointerPoints::laser_points() const {
   return points_;
 }
 }  // namespace ash