Add lifecycle observers for future mixin structures.

- Converted VisibilityLoggerMixin into a LifecyclerObservable so we
  don't have to call logger.onResume/onPause manually in most fragments.
- Observable will be useful when we provide logics across all
  fragment/activity, eg log lifecycle event latencies.
- Also added new tests for lifecycle component.

Bug: 30681529
Test: RunSettingsRoboTests

Change-Id: Ida39300aeb42f71b2e0bbfaebd0c51dc468cb5e8

src/com/android/settings/UserDictionarySettings.java

@@ -70,7 +70,7 @@ public class UserDictionarySettings extends ListFragment implements Instrumentab
     private static final int OPTIONS_MENU_ADD = Menu.FIRST;
 
     private final VisibilityLoggerMixin mVisibilityLoggerMixin =
-            new VisibilityLoggerMixin(this);
+            new VisibilityLoggerMixin(getMetricsCategory());
 
     private Cursor mCursor;
     protected String mLocale;
@@ -128,7 +128,7 @@ public class UserDictionarySettings extends ListFragment implements Instrumentab
     @Override
     public void onResume() {
         super.onResume();
-        mVisibilityLoggerMixin.onResume(getActivity());
+        mVisibilityLoggerMixin.onResume();
     }
 
     private Cursor createCursor(final String locale) {
@@ -192,7 +192,7 @@ public class UserDictionarySettings extends ListFragment implements Instrumentab
     @Override
     public void onPause() {
         super.onPause();
-        mVisibilityLoggerMixin.onPause(getActivity());
+        mVisibilityLoggerMixin.onPause();
     }
 
     /**