Fixing regression when animating in new views after dismissing task.

- In the old stack, the range of stack task progress was 0..1, but now
  it needs to be offset by the stack range.

Change-Id: I21cb5c7c8c3cc3648867626a516de9ab01e704c8

packages/SystemUI/src/com/android/systemui/recents/views/TaskStackLayoutAlgorithm.java

@@ -504,6 +504,15 @@ public class TaskStackLayoutAlgorithm {
         return 0f;
     }
 
+    /**
+     * Returns the task progress that would put the task just off the front of the stack.
+     */
+    public float getStackFrontTaskProgress(float stackScroll) {
+        float max = mUnfocusedRange.relativeMax +
+                mFocusState * (mFocusedRange.relativeMax - mUnfocusedRange.relativeMax);
+        return stackScroll + max;
+    }
+
     /**
      * Computes the maximum number of visible tasks and thumbnails when the scroll is at the initial
      * stack scroll.  Requires that update() is called first.

packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java

@@ -517,8 +517,9 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
                         } else {
                             if (!hasStackFrontTransform) {
                                 hasStackFrontTransform = true;
-                                mLayoutAlgorithm.getStackTransform(1f, 0f, mTmpStackFrontTransform,
-                                        null);
+                                mLayoutAlgorithm.getStackTransform(
+                                        mLayoutAlgorithm.getStackFrontTaskProgress(0f), 0f,
+                                        mTmpStackFrontTransform, null);
                             }
                             tv.updateViewPropertiesToTaskTransform(mTmpStackFrontTransform, 0, 0,
                                     mFastOutSlowInInterpolator, mRequestUpdateClippingListener);