Revert to passing mIsStashed to StashedHandleViewController again

- Fixes case where handle is initially invisible but will be stashed
  and visible, e.g. when launching an app from home screen
- To fix the original issue of sampling happening unnecessarily for
  three button nav, also check supportsVisualStashing()

Fixes: 321257120
Flag: None
Test: Launch an app from home in gesture nav mode
Test: testThreeButtonsTaskbarBoundsAfterConfigChangeDuringIme
Change-Id: I1f26436de3081fd00f75a5921010e361e9a9f34e

quickstep/src/com/android/launcher3/taskbar/StashedHandleViewController.java

@@ -155,7 +155,7 @@ public class StashedHandleViewController implements TaskbarControllers.LoggableT
         });
         initRegionSampler();
         if (mActivity.isPhoneGestureNavMode()) {
-            onIsStashedChanged();
+            onIsStashedChanged(true);
         }
     }
 
@@ -238,8 +238,8 @@ public class StashedHandleViewController implements TaskbarControllers.LoggableT
     }
 
     /** Called when taskbar is stashed or unstashed. */
-    public void onIsStashedChanged() {
-        mIsStashed = isStashedHandleVisible();
+    public void onIsStashedChanged(boolean isStashed) {
+        mIsStashed = isStashed;
         updateSamplingState();
     }