Move default pip position to right above the shelf (Pt. Launcher)

SysUI change: ag/3721784, ag/3793664

- Track LauncherState and launcher activity state through callbacks.
- Devise logic to send shelf visibility and height signal to SysUI based
on LauncherState and Launcher activity state.

Bug: 73961893
Test:
- By default, pip shows up right above the shelf.
- Transitioning to all apps moves the pip down as the shelf becomes
invisible.
- Going to any specific app moves pip down. Hitting home moves pip
right above the shelf again.
- Dismissing IME should push PIP down but above the shelf on home
screen, bottom if not.

Change-Id: I1ab6ceb8007a5a7b5d932a456efa0a07f586ea4c

src/com/android/launcher3/BaseActivity.java

@@ -39,6 +39,7 @@ public abstract class BaseActivity extends Activity {
     protected SystemUiController mSystemUiController;
 
     private boolean mStarted;
+    private boolean mUserActive;
 
     public DeviceProfile getDeviceProfile() {
         return mDeviceProfile;
@@ -84,6 +85,18 @@ public abstract class BaseActivity extends Activity {
         super.onStart();
     }
 
+    @Override
+    protected void onResume() {
+        mUserActive = true;
+        super.onResume();
+    }
+
+    @Override
+    protected void onUserLeaveHint() {
+        mUserActive = false;
+        super.onUserLeaveHint();
+    }
+
     @Override
     protected void onStop() {
         mStarted = false;
@@ -94,6 +107,10 @@ public abstract class BaseActivity extends Activity {
         return mStarted;
     }
 
+    public boolean isUserActive() {
+        return mUserActive;
+    }
+
     public void addOnDeviceProfileChangeListener(OnDeviceProfileChangeListener listener) {
         mDPChangeListeners.add(listener);
     }