Correct the usage of finalize in TracingControllerAndroid class.

content/public/android/java/src/org/chromium/content/browser/TracingControllerAndroid.java

 // Copyright 2013 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.content.browser;
 
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
@@ skipping 224 matching lines @@
     public void getCategoryGroups() {
         // Lazy initialize the native side, to allow construction before the library is loaded.
         initializeNativeControllerIfNeeded();
         if (!nativeGetKnownCategoryGroupsAsync(mNativeTracingControllerAndroid)) {
             Log.e(TAG, "Unable to fetch tracing record groups list.");
         }
     }
 
     @Override
     protected void finalize() {
+        // Ensure that destroy() was called.
+        assert mNativeTracingControllerAndroid == 0;
+    }
+
+    /**
+     * Clean up the C++ side of this class.
+     * After the call, this class instance shouldn't be used.
+     */
+    public void destroy() {
         if (mNativeTracingControllerAndroid != 0) {
             nativeDestroy(mNativeTracingControllerAndroid);
             mNativeTracingControllerAndroid = 0;
         }
     }
 
     private void logAndToastError(String str) {
         Log.e(TAG, str);
         if (mShowToasts) Toast.makeText(mContext, str, Toast.LENGTH_SHORT).show();
     }
@@ skipping 46 matching lines @@
 
     private long mNativeTracingControllerAndroid;
     private native long nativeInit();
     private native void nativeDestroy(long nativeTracingControllerAndroid);
     private native boolean nativeStartTracing(
             long nativeTracingControllerAndroid, String categories, boolean recordContinuously);
     private native void nativeStopTracing(long nativeTracingControllerAndroid, String filename);
     private native boolean nativeGetKnownCategoryGroupsAsync(long nativeTracingControllerAndroid);
     private native String nativeGetDefaultCategories();
 }