Add stretch overscroll to ViewPager

Bug: 171228096

Relnote: "Adds stretch overscroll support to ViewPager"

Test: new tests. ran existing ViewPager tests.

Change-Id: I79d4e0a9dadac5b855ad2504271b2e7723479efc

diff --git a/viewpager/viewpager/api/public_plus_experimental_current.txt b/viewpager/viewpager/api/public_plus_experimental_current.txt
index c0a4ddd..e8231bd 100644
--- a/viewpager/viewpager/api/public_plus_experimental_current.txt
+++ b/viewpager/viewpager/api/public_plus_experimental_current.txt

@@ -63,6 +63,7 @@
     method public void fakeDragBy(float);
     method public androidx.viewpager.widget.PagerAdapter? getAdapter();
     method public int getCurrentItem();
+    method public int getEdgeEffectType();
     method public int getOffscreenPageLimit();
     method public int getPageMargin();
     method public boolean isDragInGutterEnabled();
@@ -76,6 +77,7 @@
     method public void setCurrentItem(int);
     method public void setCurrentItem(int, boolean);
     method public void setDragInGutterEnabled(boolean);
+    method public void setEdgeEffectType(int);
     method public void setOffscreenPageLimit(int);
     method @Deprecated public void setOnPageChangeListener(androidx.viewpager.widget.ViewPager.OnPageChangeListener!);
     method public void setPageMargin(int);