Improve orientation sensing when waking up while flat.

This change makes the window manager pass the currently displayed
orientation to the WindowOrientationListener each time to calls to get
the currently sensed orientation.  Now, when the
WindowOrientationListener doesn't know for sure what the orientation
of the device should be (for example, if the sensed orientation is
flat on a table), then it trusts the already-displayed orientation,
rather than trusting whatever sensors reading it most recently
received.

The main use case this addresses is:
* user uses device in portrait
* user turns off device, puts it in pocket
* while in pocket, screen gets turned on, activating orientaiton
  sensor, which senses landscape orientation
* screen timed out
* user takes device out, places it on a table (or looks down at it,
  holding it flat), and unlocks it

Previously, when the device was unlocked, the
WindowOrientationListener would return landscape orientation based on
its previous sensor readings.  Now, it will override those previous
readings because it knows they never actually took effect and the
device is presently flat.

This change also slightly modifies the way we handle flat orientation,
now completely ignoring data when the tilt distrust is nonzero (even
if the current sensor reading shows non-tilted).

Change-Id: Ia4950a41827f8c53a80487d0c2e83b556df781b9

1 files changed, 1 insertions, 3 deletions

diff --git a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
index e2e6f1a..274124b 100755
--- a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
+++ b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
@@ -2076,9 +2076,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                 return mDeskDockRotation;
             } else {
                 if (useSensorForOrientationLp(orientation)) {
-                    // If the user has enabled auto rotation by default, do it.
-                    int curRotation = mOrientationListener.getCurrentRotation();
-                    return curRotation >= 0 ? curRotation : lastRotation;
+                    return mOrientationListener.getCurrentRotation(lastRotation);
                 }
                 return Surface.ROTATION_0;
             }