Prerequisites for TAPL

Adding things that will be used by TAPL.

1. Adding Ctrl+W to open widgets
2. Marking a UI element with shortcuts_and_widgets
id. Example of usage: we want to be sure we are in all apps.
A somewhat paranoid way to check this is to check that
apps_view is on, and workspace and overview_panel are off.
However, workspace is always in the hierarchy. We use
shortcuts_and_widgets instead.

Bug: 110103162
Test: Manual
Change-Id: I2a851e16c477f7ee895b459530bc5a1ff19e32f8

src/com/android/launcher3/Workspace.java

@@ -547,6 +547,7 @@ public class Workspace extends PagedView<WorkspacePageIndicator>
         // created CellLayout.
         CellLayout newScreen = (CellLayout) LayoutInflater.from(getContext()).inflate(
                         R.layout.workspace_screen, this, false /* attachToRoot */);
+        newScreen.getShortcutsAndWidgets().setId(R.id.workspace_page_container);
         int paddingLeftRight = mLauncher.getDeviceProfile().cellLayoutPaddingLeftRightPx;
         int paddingBottom = mLauncher.getDeviceProfile().cellLayoutBottomPaddingPx;
         newScreen.setPadding(paddingLeftRight, 0, paddingLeftRight, paddingBottom);