Add PageIndicator interface and custom PageIndicatorLine view.

- The current PageIndicator has been renamed to PageIndicatorDots
  and PageIndicatorMarker has been renamed to PageIndicatorDot.
- PageIndicatorDots and PageIndicatorLine implement PageIndicator.
- PageIndicatorLine uses scroll progress and number of pages to
  draw a line of the correct size and position.
- All of these page indicator files are now in a pageindicators package.

Bug: 27227498

Change-Id: I9230d2e0600ce583989bd31d0b0e252b148d15c2
diff --git a/res/layout-sw720dp/launcher.xml b/res/layout-sw720dp/launcher.xml
index 780d645..0f755d8 100644
--- a/res/layout-sw720dp/launcher.xml
+++ b/res/layout-sw720dp/launcher.xml
@@ -64,11 +64,10 @@
 
         <!-- Keep these behind the workspace so that they are not visible when
              we go into AllApps -->
-        <include android:id="@+id/page_indicator"
-            layout="@layout/page_indicator"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_gravity="center_horizontal" />
+        <com.android.launcher3.pageindicators.PageIndicatorLine
+            android:id="@+id/page_indicator"
+            android:layout_width="match_parent"
+            android:layout_height="1dp" />
 
         <include layout="@layout/widgets_view"
             android:id="@+id/widgets_view"