[Cronet] Regression test for DCHECK when histograms read on another thread

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;
@@ skipping 13 matching lines @@
 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;
 import java.net.URL;
 import java.util.Arrays;
+import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
+import java.util.concurrent.FutureTask;
 import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * Test CronetEngine.
  */
 @JNINamespace("cronet")
 public class CronetUrlRequestContextTest extends CronetTestBase {
     private static final String TAG = CronetUrlRequestContextTest.class.getSimpleName();
 
     // URLs used for tests.
@@ skipping 1100 matching lines @@
     public void testGetGlobalMetricsDeltas() throws Exception {
         final CronetTestFramework testFramework = startCronetTestFramework();
 
         byte delta1[] = testFramework.mCronetEngine.getGlobalMetricsDeltas();
 
         TestUrlRequestCallback callback = new TestUrlRequestCallback();
         UrlRequest.Builder builder = testFramework.mCronetEngine.newUrlRequestBuilder(
                 mUrl, callback, callback.getExecutor());
         builder.build().start();
         callback.blockForDone();
-        byte delta2[] = testFramework.mCronetEngine.getGlobalMetricsDeltas();
+        // Fetch deltas on a different thread the second time to make sure this is permitted.
+        // See crbug.com/719448
+        FutureTask<byte[]> task = new FutureTask<byte[]>(new Callable<byte[]>() {
+            public byte[] call() {
+                return testFramework.mCronetEngine.getGlobalMetricsDeltas();
+            }
+        });
+        new Thread(task).start();
+        byte delta2[] = task.get();
         assertTrue(delta2.length != 0);
         assertFalse(Arrays.equals(delta1, delta2));
     }
 
     @SmallTest
     @Feature({"Cronet"})
     public void testCronetEngineBuilderConfig() throws Exception {
         // This is to prompt load of native library.
         startCronetTestFramework();
         // Verify CronetEngine.Builder config is passed down accurately to native code.
@@ skipping 94 matching lines @@
         TestUrlRequestCallback callback = new TestUrlRequestCallback();
         URL requestUrl =
                 new URL("http", resolverTestHostname, testUrl.getPort(), testUrl.getFile());
         UrlRequest.Builder urlRequestBuilder = testFramework.mCronetEngine.newUrlRequestBuilder(
                 requestUrl.toString(), callback, callback.getExecutor());
         urlRequestBuilder.build().start();
         callback.blockForDone();
         assertEquals(200, callback.mResponseInfo.getHttpStatusCode());
     }
 }