WidgetCell will use the generated RemoteViews preview to display
previews in the widget picker. It will fallback to current preview
methods if not available.
Introduces WidgetManagerHelper.loadGeneratedPreviews as a utility
function. WidgetManagerHelper is passed into the constructor of
WidgetItem to avoid calling
context.getSystemService(AppWidgetManager.class) for each widget.
Bug: 308041327
Test: atest Launcher3Tests:GeneratedPreviewTest
Flag: ACONFIG com.android.launcher3.enable_generated_previews DEVELOPMENT
Change-Id: I37429057cda83a5321884ace2537038e050b9a58
Willie Koomson
fedc18e9a8