Don't crash on opening ejecting USB.

This crash occurs because, even if you finish an Activity during
onCreate, the other lifecycle methods occur. In this case,
onActivityCreated assumes that onCreate ran properly.

By exiting early from onActivityCreated, we can ensure the activity
is finished properly.

Change-Id: Ia354341bf82d295c7dd042668fb11d588ddfebc0
Fixes: 37334861
Test: Instrumentation test

src/com/android/settings/deviceinfo/PublicVolumeSettings.java

@@ -98,7 +98,9 @@ public class PublicVolumeSettings extends SettingsPreferenceFragment {
             mVolume = mStorageManager.findVolumeByUuid(fsUuid);
         } else {
             final String volId = getArguments().getString(VolumeInfo.EXTRA_VOLUME_ID);
-            mVolume = mStorageManager.findVolumeById(volId);
+            if (volId != null) {
+                mVolume = mStorageManager.findVolumeById(volId);
+            }
         }
 
         if (!isVolumeValid()) {
@@ -129,6 +131,12 @@ public class PublicVolumeSettings extends SettingsPreferenceFragment {
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
+
+        // If the volume isn't valid, we are not scaffolded to set up a view.
+        if (!isVolumeValid()) {
+            return;
+        }
+
         final Resources resources = getResources();
         final int padding = resources.getDimensionPixelSize(
                 R.dimen.unmount_button_padding);

tests/unit/src/com/android/settings/deviceinfo/PublicVolumeSettingsTest.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2017 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.deviceinfo;
+
+import android.content.Intent;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.android.settings.Settings;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class PublicVolumeSettingsTest {
+    @Rule
+    public ActivityTestRule<Settings.PublicVolumeSettingsActivity> mActivityRule =
+            new ActivityTestRule<>(Settings.PublicVolumeSettingsActivity.class, true, true);
+
+    @Test
+    public void test_invalidSetupDoesNotCrashSettings() {
+        Intent intent = new Intent();
+        intent.setAction(android.provider.Settings.ACTION_INTERNAL_STORAGE_SETTINGS);
+        intent.setClassName(InstrumentationRegistry.getTargetContext().getPackageName(),
+                Settings.PublicVolumeSettingsActivity.class.getName());
+        mActivityRule.launchActivity(intent);
+
+        // Should exit gracefully without crashing.
+    }
+}