Fix the horizontal margins on the left panel in the two pane picker.

The recycler view when displayed in single pane picker, for large screen
gets a larger padding. But when displayed in two pane picker, it is not
needed - so we override it.

Foldable's unfolded portrait doesn't seem to have screenshot test
- will look into if we can add one in follow up.

Bug: 322719955
Test: Screenshot test for existing modes & manual (see bug)
Flag: ACONFIG com.android.launcher3.enable_unfolded_two_pane_picker DEVELOPMENT

Change-Id: Ibd72146e7e5230eec0d2ce01c3917819a73d8f32

src/com/android/launcher3/widget/BaseWidgetSheet.java

@@ -72,14 +72,21 @@ public abstract class BaseWidgetSheet extends AbstractSlideInView<BaseActivity>
 
     public BaseWidgetSheet(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
-        mContentHorizontalMargin = getResources().getDimensionPixelSize(
-                R.dimen.widget_list_horizontal_margin);
+        mContentHorizontalMargin = getWidgetListHorizontalMargin();
         mWidgetCellHorizontalPadding = getResources().getDimensionPixelSize(
                 R.dimen.widget_cell_horizontal_padding);
         mNavBarScrimPaint = new Paint();
         mNavBarScrimPaint.setColor(Themes.getNavBarScrimColor(mActivityContext));
     }
 
+    /**
+     * Returns the margins to be applied to the left and right of the widget apps list.
+     */
+    protected int getWidgetListHorizontalMargin() {
+        return getResources().getDimensionPixelSize(
+                R.dimen.widget_list_horizontal_margin);
+    }
+
     protected int getScrimColor(Context context) {
         return context.getResources().getColor(R.color.widgets_picker_scrim);
     }
@@ -142,8 +149,7 @@ public abstract class BaseWidgetSheet extends AbstractSlideInView<BaseActivity>
     @Override
     public void setInsets(Rect insets) {
         mInsets.set(insets);
-        @Px int contentHorizontalMargin = getResources().getDimensionPixelSize(
-                R.dimen.widget_list_horizontal_margin);
+        @Px int contentHorizontalMargin = getWidgetListHorizontalMargin();
         if (contentHorizontalMargin != mContentHorizontalMargin) {
             onContentHorizontalMarginChanged(contentHorizontalMargin);
             mContentHorizontalMargin = contentHorizontalMargin;