Remove the toolbar icon from DocumentsUI.

Bug: 27565928
Change-Id: I5181466a770e11716f173cf8cc66f62ba71ac710

packages/DocumentsUI/src/com/android/documentsui/NavigationView.java

@@ -147,17 +147,13 @@ class NavigationView {
         }
     }
 
-    // Hamburger if drawer is present, else root icon, or sad nullness.
+    // Hamburger if drawer is present, else sad nullness.
     private @Nullable Drawable getActionBarIcon() {
         if (mDrawer.isPresent()) {
             return mToolbar.getContext().getDrawable(R.drawable.ic_hamburger);
         } else {
-            RootInfo root = mEnv.getCurrentRoot();
-            if (root != null) {
-                return root.loadToolbarIcon(mToolbar.getContext());
-            }
+            return null;
         }
-        return null;
     }
 
     void revealRootsDrawer(boolean open) {

packages/DocumentsUI/src/com/android/documentsui/model/RootInfo.java

@@ -334,15 +334,6 @@ public class RootInfo implements Durable, Parcelable, Comparable<RootInfo> {
         }
     }
 
-    public Drawable loadToolbarIcon(Context context) {
-        if (derivedIcon != 0) {
-            return IconUtils.applyTintAttr(context, derivedIcon,
-                    android.R.attr.colorControlNormal);
-        } else {
-            return IconUtils.loadPackageIcon(context, authority, icon);
-        }
-    }
-
     @Override
     public boolean equals(Object o) {
         if (o == null) {