Convert ChromeActivityTestCaseBase direct children to JUnit4

chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java
index 2465227c6ca82c89361a36453d2191cbbb7ef9b2..f2a69ea8fcaa5058ab263f4b3781392c7fd7fa4d 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/AudioTest.java
@@ -4,9 +4,20 @@
 
 package org.chromium.chrome.browser;
 
+import android.support.test.InstrumentationRegistry;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.FlakyTest;
 import org.chromium.chrome.browser.tab.Tab;
-import org.chromium.chrome.test.ChromeActivityTestCaseBase;
+import org.chromium.chrome.test.ChromeActivityTestRule;
+import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 import org.chromium.chrome.test.util.browser.TabTitleObserver;
 import org.chromium.content.browser.test.util.DOMUtils;
 import org.chromium.net.test.EmbeddedTestServer;
@@ -16,24 +27,26 @@ import java.util.concurrent.TimeoutException;
 /**
  * Simple HTML5 audio tests.
  */
-public class AudioTest extends ChromeActivityTestCaseBase<ChromeActivity> {
+@RunWith(ChromeJUnit4ClassRunner.class)
+@CommandLineFlags.Add({ChromeSwitches.DISABLE_FIRST_RUN_EXPERIENCE,

[Ted C, 2017/04/27 18:05:27]

Create an array constant in ChromeActivityTestRule (or somewhere) for the
default Chrome test flags.  Having to duplicate these in every file is sad (and
if we need to add a new default flag that would be super painful).

[the real yoland, 2017/04/28 02:03:28]

Commented below.

[Ted C, 2017/04/28 22:57:46]

I don't see why the below comment prevents us from adding a constant now.  Even
if we want to move it to a rule later, I would rather us make it better in the
meantime and introducing a constant seems ok.

For the cases where classes need to add additional flags, then they can still
include them all but for the bulk of the classes that just need the defaults it
should just be a string.

[the real yoland, 2017/05/01 23:05:02]

Hmm, my bad, I just realized one can't add array variable to an annotation.

e.g.
public static String[] DEFAULT_FLAGS = new String[] {"a", "b"};

@CommandLineFlags.Add(DEFAULT_FLAGS) //can not compile because a compile-time
constant is required as an annotation element, which means only enum, string,
primitive types :(

If we want to avoid repeating the same flags and also avoid using base classes,
maybe we can create an interface just for CommandLineFlags annotations.

e.g.
```
@CommandLineFlag.Add({a, b})
public inteface ChromeDefaultFlags {}

public class AudioTest implements ChromeDefaultFlags {...}
```

This does require some implementation change on
CommandLineFlags#getFlags(AnnotatedElement e)

but if commandline flags annotations are eventually to be replaced by test
rules, this might be a weird standard for a transitional stage for someone who
write tests

What do y'all think?

[Ted C, 2017/05/02 00:09:55]

Sadness.  I don't know if I would go down that path.  We can likely just leave
it as it :-/

+        ChromeActivityTestRule.DISABLE_NETWORK_PREDICTION_FLAG})
+public class AudioTest {
+    @Rule
+    public ChromeActivityTestRule<ChromeActivity> mActivityTestRule =
+            new ChromeActivityTestRule<>(ChromeActivity.class);
 
     private EmbeddedTestServer mTestServer;
 
-    public AudioTest() {
-        super(ChromeActivity.class);
-    }
-
-    @Override
-    protected void setUp() throws Exception {
-        super.setUp();
-        mTestServer = EmbeddedTestServer.createAndStartServer(getInstrumentation().getContext());
+    @Before
+    public void setUp() throws Exception {
+        mActivityTestRule.startMainActivityOnBlankPage();
+        mTestServer = EmbeddedTestServer.createAndStartServer(
+                InstrumentationRegistry.getInstrumentation().getContext());
     }
 
-    @Override
-    protected void tearDown() throws Exception {
+    @After
+    public void tearDown() throws Exception {
         mTestServer.stopAndDestroyServer();
-        super.tearDown();
     }
 
     /**
@@ -42,24 +55,21 @@ public class AudioTest extends ChromeActivityTestCaseBase<ChromeActivity> {
      * @MediumTest
      */
     // TODO(jbudorick): Attempt to reenable this after the server switch has stabilized.
+    @Test
     @FlakyTest(message = "crbug.com/331122")
     public void testPlayMp3() throws InterruptedException, TimeoutException {
-        Tab tab = getActivity().getActivityTab();
+        Tab tab = mActivityTestRule.getActivity().getActivityTab();
         TabTitleObserver titleObserver = new TabTitleObserver(tab, "ready_to_play");
-        loadUrl(mTestServer.getURL("/chrome/test/data/android/media/audio-play.html"));
+        mActivityTestRule.loadUrl(
+                mTestServer.getURL("/chrome/test/data/android/media/audio-play.html"));
         titleObserver.waitForTitleUpdate(5);
-        assertEquals("ready_to_play", tab.getTitle());
+        Assert.assertEquals("ready_to_play", tab.getTitle());
 
         titleObserver = new TabTitleObserver(tab, "ended");
         DOMUtils.clickNode(tab.getContentViewCore(), "button1");
 
         // Make sure that the audio playback "ended" and title is changed.
         titleObserver.waitForTitleUpdate(15);
-        assertEquals("ended", tab.getTitle());
-    }
-
-    @Override
-    public void startMainActivity() throws InterruptedException {
-        startMainActivityOnBlankPage();
+        Assert.assertEquals("ended", tab.getTitle());
     }
 }