Prevent unintended rotations.

Bug: 4981385

Changed the orientation listener to notify the policy whenever
its proposed orientation changes, and changes the window manager
to notify the orientation listener when the actual orientation
changes.  This allows us to better handle the case where the
policy has rejected a given proposal at one time (because the
current application forced orientation) but might choose
to accept the same proposal at another time.

It's important that the proposal always be up to date.  A proposal
becomes irrelevant as soon as the phone posture changes such
that we can no longer determine the orientation with confidence
(such as when a device is placed flat on a table).

Simplified the orientation filtering.  Now we just wait 200ms
for the device to be still before issuing a proposal.  The idea
is that if the device is moving around a lot, we assume that
the device is being picked up or put down or otherwise in
the process of being moved.  We don't want to change the rotation
until that's all settled down.  However, we do want to tolerate
a certain amount of environmental noise.

(The previous confidence algorithm was also designed along
these lines but it was less direct about waiting for things
to settle.  Instead it simply made orientation changes take
longer than usual while unsettled, but the extra delay was often
too much or too little.  This one should be easier to tune.)

Change-Id: I09e6befea1f0994b6b15d424f3182859c0d9a530

Author: Jeff Brown

core/java/android/view/WindowManagerPolicy.java

@@ -875,6 +875,13 @@ interface OnKeyguardExitResult {
      */
     public boolean rotationHasCompatibleMetricsLw(int orientation, int rotation);
 
+    /**
+     * Called by the window manager when the rotation changes.
+     *
+     * @param rotation The new rotation.
+     */
+    public void setRotationLw(int rotation);
+
     /**
      * Called when the system is mostly done booting to determine whether
      * the system should go into safe mode.