Fix race causing crash in net::FileNetLogObserver shutdown

components/cronet/android/test/javatests/src/org/chromium/net/CronetUrlRequestContextTest.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import android.content.Context;
 import android.content.ContextWrapper;
 import android.os.ConditionVariable;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Process;
 import android.support.test.filters.SmallTest;
 
 import org.json.JSONObject;
 
 import static org.chromium.net.CronetEngine.Builder.HTTP_CACHE_IN_MEMORY;
 
 import org.chromium.base.FileUtils;
 import org.chromium.base.PathUtils;
 import org.chromium.base.annotations.JNINamespace;
-import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
 import org.chromium.net.TestUrlRequestCallback.ResponseStep;
 import org.chromium.net.impl.CronetEngineBuilderImpl;
 import org.chromium.net.impl.CronetLibraryLoader;
 import org.chromium.net.impl.CronetUrlRequestContext;
 import org.chromium.net.test.EmbeddedTestServer;
 
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
@@ skipping 447 matching lines @@
         // Make sure both files contain the two requests made separately using
         // different engines.
         assertTrue(containsStringInNetLog(file1, mUrl404));
         assertTrue(containsStringInNetLog(file1, mUrl500));
         assertTrue(containsStringInNetLog(file2, mUrl404));
         assertTrue(containsStringInNetLog(file2, mUrl500));
         assertTrue(file1.delete());
         assertTrue(file2.delete());
     }
 
-    //@SmallTest
-    //@Feature({"Cronet"})
-    //@OnlyRunNativeCronet
-    // Frequently crashes on Cronet builders - see crbug.com/729257
-    @DisabledTest
+    @SmallTest
+    @Feature({"Cronet"})
+    @OnlyRunNativeCronet
     // Tests that NetLog contains events emitted by all live CronetEngines.
     public void testBoundedFileNetLogContainEventsFromAllLiveEngines() throws Exception {
         Context context = getContext();
         File directory = new File(PathUtils.getDataDirectory());
         File netLogDir1 = new File(directory, "NetLog1");
         assertFalse(netLogDir1.exists());
         assertTrue(netLogDir1.mkdir());
         File netLogDir2 = new File(directory, "NetLog2");
         assertFalse(netLogDir2.exists());
         assertTrue(netLogDir2.mkdir());
@@ skipping 821 matching lines @@
         }
         // Test that valid thread priority range (-20..19) is working.
         for (int threadPriority = -20; threadPriority < 20; threadPriority++) {
             builder.setThreadPriority(threadPriority);
             CronetEngine engine = builder.build();
             assertEquals(threadPriority, getThreadPriority(engine));
             engine.shutdown();
         }
     }
 }