Add blob size to shared data dev options screens.

Bug: 156671006
Test: make RunSettingsRoboTests ROBOTEST_FILTER=SharedDataPreferenceControllerTest
Test: manual (visual)
Change-Id: Ia98c3d9812f6225ee834b4d1b0f12a1a73a87598

src/com/android/settings/development/storage/SharedDataUtils.java

@@ -39,4 +39,9 @@ class SharedDataUtils {
         CALENDAR.setTimeInMillis(millis);
         return FORMATTER.format(CALENDAR.getTime());
     }
+
+    static String formatSize(long sizeBytes) {
+        final double sizeInMb = sizeBytes / (1024.0 * 1024.0);
+        return String.format("%.2f MB", sizeInMb);
+    }
 }