For supoorting new API as below, the A11y window cache needs to modify from one dimension to two dimension. The first dimension is window Id, the second(new) dimention is the display Id. SparseArray<List<AccessibilityWindowInfo>> getWindowsOnAllDisplays() Bug: 133279356 Test: a11y CTS & unit tests Change-Id: Ida49ef22de67bd81353a896491dcae56ed751fd1