[Cronet] HistogramManager now ensures that StatisticsRecorder is initialized.

components/cronet/android/java/src/org/chromium/net/HistogramManager.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 org.chromium.base.JNINamespace;
 
 /**
  * Controls UMA histograms.
  */
 @JNINamespace("cronet")
 public final class HistogramManager {
     public HistogramManager() {
+        nativeEnsureInitialized();
     }
 
     /**
      * Get histogram deltas serialized as protobuf.
      */
     public byte[] getHistogramDeltas() {
         return nativeGetHistogramDeltas();
     }
 
     private native byte[] nativeGetHistogramDeltas();
+
+    private native void nativeEnsureInitialized();
 }