Export the instance of CoordinatorLayout

Providing an API to access to the instance of CoordinatorLayout in
collapsing_toolbar_base_layout, that facilitates the insertion of
components as a direct child of CoordinatorLayout.

Bug: 189423430
Test: rebuild permission controller apk
Change-Id: Iebd7a6cd0cb5bdc38c70343a86736e91f58ce254

packages/SettingsLib/CollapsingToolbarBaseActivity/src/com/android/settingslib/collapsingtoolbar/CollapsingToolbarBaseFragment.java

@@ -41,6 +41,8 @@ public abstract class CollapsingToolbarBaseFragment extends Fragment implements
     private static final int FULLY_EXPANDED_OFFSET = 0;
     private static final String KEY_IS_TOOLBAR_COLLAPSED = "is_toolbar_collapsed";
 
+    @Nullable
+    private CoordinatorLayout mCoordinatorLayout;
     @Nullable
     private CollapsingToolbarLayout mCollapsingToolbarLayout;
     @Nullable
@@ -57,6 +59,7 @@ public abstract class CollapsingToolbarBaseFragment extends Fragment implements
             @Nullable Bundle savedInstanceState) {
         final View view = inflater.inflate(R.layout.collapsing_toolbar_base_layout, container,
                 false);
+        mCoordinatorLayout = view.findViewById(R.id.content_parent);
         mCollapsingToolbarLayout = view.findViewById(R.id.collapsing_toolbar);
         mAppBarLayout = view.findViewById(R.id.app_bar);
         mAppBarLayout.addOnOffsetChangedListener(this);
@@ -94,6 +97,14 @@ public abstract class CollapsingToolbarBaseFragment extends Fragment implements
         }
     }
 
+    /**
+     * Return an instance of CoordinatorLayout.
+     */
+    @Nullable
+    public CoordinatorLayout getCoordinatorLayout() {
+        return mCoordinatorLayout;
+    }
+
     /**
      * Return an instance of app bar.
      */