Fix policy issues when screen is off. (DO NOT MERGE)

Rewrote interceptKeyBeforeQueueing to make the handling more systematic.
Behavior should be identical except:
- We never pass keys to applications when the screen is off and the keyguard
  is not showing (the proximity sensor turned off the screen).
  Previously we passed all non-wake keys through in this case which
  caused a bug on Crespo where the screen would come back on if a soft key
  was held at the time of power off because the resulting key up event
  would sneak in just before the keyguard was shown.  It would then be
  passed through to the dispatcher which would poke user activity and
  wake up the screen.
- We propagate the key flags when broadcasting media keys which
  ensures that recipients can tell when the key is canceled.
- We ignore endcall or power if canceled (shouldn't happen anyways).

Changed the input dispatcher to not poke user activity for canceled
events since they are synthetic and should not wake the device.

Changed the lock screen so that it does not poke the wake lock when the
grab handle is released.  This fixes a bug where the screen would come
back on immediately if the power went off while the user was holding
one of the grab handles because the sliding tab would receive an up
event after screen turned off and release the grab handles.

Bug: 3144874
Change-Id: Iebb91e10592b4ef2de4b1dd3a2e1e4254aacb697

libs/ui/InputDispatcher.cpp

@@ -1405,8 +1405,13 @@ String8 InputDispatcher::getApplicationWindowLabelLocked(const InputApplication*
 
 void InputDispatcher::pokeUserActivityLocked(const EventEntry* eventEntry) {
     int32_t eventType = POWER_MANAGER_BUTTON_EVENT;
-    if (eventEntry->type == EventEntry::TYPE_MOTION) {
+    switch (eventEntry->type) {
+    case EventEntry::TYPE_MOTION: {
         const MotionEntry* motionEntry = static_cast<const MotionEntry*>(eventEntry);
+        if (motionEntry->action == AMOTION_EVENT_ACTION_CANCEL) {
+            return;
+        }
+
         if (motionEntry->source & AINPUT_SOURCE_CLASS_POINTER) {
             switch (motionEntry->action) {
             case AMOTION_EVENT_ACTION_DOWN:
@@ -1424,6 +1429,15 @@ void InputDispatcher::pokeUserActivityLocked(const EventEntry* eventEntry) {
                 break;
             }
         }
+        break;
+    }
+    case EventEntry::TYPE_KEY: {
+        const KeyEntry* keyEntry = static_cast<const KeyEntry*>(eventEntry);
+        if (keyEntry->flags & AKEY_EVENT_FLAG_CANCELED) {
+            return;
+        }
+        break;
+    }
     }
 
     CommandEntry* commandEntry = postCommandLocked(