Change display of 360 panorama button

Bug: 7300866
-Move pano button to center and make larger
-Pano button visible even when in full-screen mode
-Show edit button only when image editor is available
-Correctly hide bottom controls when switching from
 filmstrip mode to grid mode
Change-Id: I485b1988733bedd0c03e89a261a6ce80be46b9bc
diff --git a/res/layout/photopage_bottom_controls.xml b/res/layout/photopage_bottom_controls.xml
index 5b80cf2..434c598 100644
--- a/res/layout/photopage_bottom_controls.xml
+++ b/res/layout/photopage_bottom_controls.xml
@@ -15,21 +15,18 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_alignParentLeft="true"
+                android:layout_alignParentBottom="true"
                 android:paddingTop="5dp"
                 android:paddingBottom="5dp"
                 android:paddingLeft="15dp"
                 android:paddingRight="15dp"
                 android:visibility="gone"/>
-        <ImageButton
+        <ImageView
                 android:id="@+id/photopage_bottom_control_panorama"
                 android:src="@drawable/ic_menu_photosphere"
-                android:background="@drawable/photopage_bottom_button_background"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_alignParentRight="true"
-                android:paddingTop="5dp"
-                android:paddingBottom="5dp"
-                android:paddingLeft="15dp"
-                android:paddingRight="15dp"
+                android:layout_width="70dp"
+                android:layout_height="70dp"
+                android:layout_centerHorizontal="true"
+                android:layout_alignParentBottom="true"
                 android:visibility="gone"/>
 </RelativeLayout>