Cronet: fix flaky Http2Test#testHttp2

components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.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.impl;
 
 import android.os.ConditionVariable;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Process;
@@ skipping 122 matching lines @@
                     VersionSafeCallbacks.RequestFinishedInfoListener>();
 
     /**
      * Synchronize access to mCertVerifierData.
      */
     private ConditionVariable mWaitGetCertVerifierDataComplete = new ConditionVariable();
 
     /** Holds CertVerifier data. */
     private String mCertVerifierData;
 
-    private ConditionVariable mStopNetLogCompleted;
+    private volatile ConditionVariable mStopNetLogCompleted;
 
     /**
      * True if a NetLog observer is active.
      */
     @GuardedBy("mLock")
     private boolean mIsLogging;
 
     @UsedByReflection("CronetEngine.java")
     public CronetUrlRequestContext(final CronetEngineBuilderImpl builder) {
         CronetLibraryLoader.ensureInitialized(builder.getContext(), builder);
@@ skipping 136 matching lines @@
         }
     }
 
     @Override
     public void stopNetLog() {
         synchronized (mLock) {
             if (!mIsLogging) {
                 return;
             }
             checkHaveAdapter();
+            mStopNetLogCompleted = new ConditionVariable();
             nativeStopNetLog(mUrlRequestContextAdapter);
             mIsLogging = false;
-            mStopNetLogCompleted = new ConditionVariable();
         }
         mStopNetLogCompleted.block();
     }
 
     @CalledByNative
     public void stopNetLogCompleted() {
         mStopNetLogCompleted.open();
     }
 
     @Override
@@ skipping 411 matching lines @@
     @NativeClassQualifiedName("CronetURLRequestContextAdapter")
     private native void nativeProvideRTTObservations(long nativePtr, boolean should);
 
     @NativeClassQualifiedName("CronetURLRequestContextAdapter")
     private native void nativeProvideThroughputObservations(long nativePtr, boolean should);
 
     public boolean isNetworkThread(Thread thread) {
         return thread == mNetworkThread;
     }
 }