Add ObservableDialogFragment to log DialogFragments.

Bug: 30681529
Test: RunSettingsRoboTests

ObservableDialogFragment can be used as host of VisibilityLoggerMixin,
allowing us to log visibility change for all dialogs easily.

Change-Id: I973db929d8494d3756584ca60df3b2e87d96c757

src/com/android/settings/core/lifecycle/ObservableDialogFragment.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.settings.core.lifecycle;
+
+import android.app.DialogFragment;
+
+/**
+ * {@link DialogFragment} that has hooks to observe fragment lifecycle events.
+ */
+public class ObservableDialogFragment extends DialogFragment {
+
+    protected final Lifecycle mLifecycle = new Lifecycle();
+
+    @Override
+    public void onStart() {
+        mLifecycle.onStart();
+        super.onStart();
+    }
+
+    @Override
+    public void onResume() {
+        mLifecycle.onResume();
+        super.onResume();
+    }
+
+    @Override
+    public void onPause() {
+        mLifecycle.onPause();
+        super.onPause();
+    }
+
+    @Override
+    public void onStop() {
+        mLifecycle.onStop();
+        super.onStop();
+    }
+
+    @Override
+    public void onDestroy() {
+        mLifecycle.onDestroy();
+        super.onDestroy();
+    }
+
+}

tests/robotests/src/com/android/settings/core/lifecycle/LifecycleTest.java

@@ -40,13 +40,23 @@ import static org.junit.Assert.assertTrue;
 @Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
 public class LifecycleTest {
 
+    public static class TestDialogFragment extends ObservableDialogFragment {
+
+        final TestObserver mFragObserver;
+
+        public TestDialogFragment() {
+            mFragObserver = new TestObserver();
+            mLifecycle.addObserver(mFragObserver);
+        }
+    }
+
     public static class TestActivity extends ObservableActivity {
 
-        final Fragment mFragment;
+        final TestDialogFragment mFragment;
         final TestObserver mActObserver;
 
         public TestActivity() {
-            mFragment = new Fragment();
+            mFragment = new TestDialogFragment();
             mActObserver = new TestObserver();
             getLifecycle().addObserver(mActObserver);
         }
@@ -102,14 +112,19 @@ public class LifecycleTest {
         TestActivity activity = ac.get();
 
         ac.create().start();
+        assertTrue(activity.mFragment.mFragObserver.mOnStartObserved);
         assertTrue(activity.mActObserver.mOnStartObserved);
         ac.resume();
+        assertTrue(activity.mFragment.mFragObserver.mOnResumeObserved);
         assertTrue(activity.mActObserver.mOnResumeObserved);
         ac.pause();
+        assertTrue(activity.mFragment.mFragObserver.mOnPauseObserved);
         assertTrue(activity.mActObserver.mOnPauseObserved);
         ac.stop();
+        assertTrue(activity.mFragment.mFragObserver.mOnStopObserved);
         assertTrue(activity.mActObserver.mOnStopObserved);
         ac.destroy();
+        assertTrue(activity.mFragment.mFragObserver.mOnDestroyObserved);
         assertTrue(activity.mActObserver.mOnDestroyObserved);
     }
 }