Fix of flaky SdchTest#testSdchEnabled test.

components/cronet/android/test/src/org/chromium/net/SdchObserver.java

 // Copyright 2015 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.os.ConditionVariable;
 
+import junit.framework.Assert;
+
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 /**
  * Class to watch for Sdch dictionary events. The native implementation
  * unregisters itself when an event happens. Therefore, an instance of this
  * class is only able to receive a notification of the earliest event.
- * Currently, implemented events include {@link #onDictionaryAdded}.
  */
 @JNINamespace("cronet")
 public class SdchObserver {
-    protected boolean mDictionaryAlreadyPresent = false;
+    private static final int BLOCK_WAIT_TIMEOUT_SEC = 20;
     private final ConditionVariable mAddBlock = new ConditionVariable();
 
     /**
      * Constructor.
      * @param targetUrl the target url on which sdch encoding will be used.
      * @param contextAdapter the native context adapter to register the observer.
      */
     public SdchObserver(String targetUrl, long contextAdapter) {
         nativeAddSdchObserver(targetUrl, contextAdapter);
-        mAddBlock.block();
-        mAddBlock.close();
     }
 
     /**
      * Called when a dictionary is added to the SdchManager for the target url.
-     * Override this method if caller would like to get notified.
      */
     @CalledByNative
-    public void onDictionaryAdded() {
+    protected void onDictionaryAdded() {
+        mAddBlock.open();
+    }
+
+    /**
+     * Called after the observer has been registered.
+     */
+    @CalledByNative
+    protected void onAddSdchObserverCompleted() {
         // Left blank;
     }
 
+    /**
+     * Called if the dictionary was added before the observer registration.
+     */
     @CalledByNative
-    private void onAddSdchObserverCompleted() {
+    protected void onDictionarySetAlreadyPresent() {
         mAddBlock.open();
     }
 
-    @CalledByNative
-    private void onDictionarySetAlreadyPresent() {
-        mDictionaryAlreadyPresent = true;
-        mAddBlock.open();
+    public void waitForDictionaryAdded() {
+        boolean success = mAddBlock.block(BLOCK_WAIT_TIMEOUT_SEC * 1000);
+        if (!success) {
+            Assert.fail("Timeout: the dictionary hasn't been added after waiting for "
+                    + BLOCK_WAIT_TIMEOUT_SEC + " seconds");
+        }
     }
 
     private native void nativeAddSdchObserver(String targetUrl, long contextAdapter);
 }