Add support for webapk without runtimeHost

chrome/android/webapk/shell_apk/src/org/chromium/webapk/shell_apk/HostBrowserClassLoader.java

 // Copyright 2016 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.webapk.shell_apk;
 
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.os.Looper;
 import android.util.Log;
 
+import org.chromium.webapk.lib.common.WebApkConstants;
 import org.chromium.webapk.lib.common.WebApkVersionUtils;
 
 import java.io.File;
 import java.util.Scanner;
 
 /**
  * Creates ClassLoader for WebAPK-specific dex file in Chrome APK's assets.
  */
 public class HostBrowserClassLoader {
     private static final String TAG = "cr_HostBrowserClassLoader";
 
     /**
-     * Name of the shared preferences file.
-     */
-    private static final String PREF_PACKAGE = "org.chromium.webapk.shell_apk";
-
-    /**
      * Name of the shared preference for Chrome's version code.
      */
     private static final String REMOTE_VERSION_CODE_PREF =
             "org.chromium.webapk.shell_apk.version_code";
 
     /**
      * Name of the shared preference for the version number of the dynamically loaded dex.
      */
     private static final String RUNTIME_DEX_VERSION_PREF =
             "org.chromium.webapk.shell_apk.dex_version";
@@ skipping 30 matching lines @@
      * Creates ClassLoader for WebAPK dex.
      * @param context WebAPK's context.
      * @param remoteContext Host browser's context.
      * @param canaryClassName Class to load to check that ClassLoader is valid.
      * @param dexLoader DexLoader for creating ClassLoader.
      * @return The ClassLoader.
      */
     public static ClassLoader createClassLoader(
             Context context, Context remoteContext, DexLoader dexLoader, String canaryClassName) {
         SharedPreferences preferences =
-                context.getSharedPreferences(PREF_PACKAGE, Context.MODE_PRIVATE);
+                context.getSharedPreferences(WebApkConstants.PREF_PACKAGE, Context.MODE_PRIVATE);
 
         int runtimeDexVersion = preferences.getInt(RUNTIME_DEX_VERSION_PREF, -1);
         int newRuntimeDexVersion = checkForNewRuntimeDexVersion(preferences, remoteContext);
         if (newRuntimeDexVersion == -1) {
             newRuntimeDexVersion = runtimeDexVersion;
         }
         File localDexDir = context.getDir("dex", Context.MODE_PRIVATE);
         if (newRuntimeDexVersion != runtimeDexVersion) {
             Log.w(TAG, "Delete cached dex files.");
             dexLoader.deleteCachedDexes(localDexDir);
         }
 
         String dexAssetName = WebApkVersionUtils.getRuntimeDexName(newRuntimeDexVersion);
         File remoteDexFile =
                 new File(remoteContext.getDir("dex", Context.MODE_PRIVATE), dexAssetName);
         return dexLoader.load(
                 remoteContext, dexAssetName, canaryClassName, remoteDexFile, localDexDir);
     }
 
     /**
      * Returns whether {@link sClassLoader} can be reused.
      */
     public static boolean canReuseClassLoaderInstance(Context context, Context remoteContext) {
         // WebAPK may still be running when the host browser gets upgraded. Prevent ClassLoader from
         // getting reused in this scenario.
         SharedPreferences preferences =
-                context.getSharedPreferences(PREF_PACKAGE, Context.MODE_PRIVATE);
+                context.getSharedPreferences(WebApkConstants.PREF_PACKAGE, Context.MODE_PRIVATE);
         int cachedRemoteVersionCode = preferences.getInt(REMOTE_VERSION_CODE_PREF, -1);
         int remoteVersionCode = getVersionCode(remoteContext);
         return remoteVersionCode == cachedRemoteVersionCode;
     }
 
     /**
      * Checks if there is a new "runtime dex" version number. If there is a new version number,
      * updates SharedPreferences.
      * @param preferences WebAPK's SharedPreferences.
      * @param remoteContext
@@ skipping 57 matching lines @@
         return value;
     }
 
     /**
      * Asserts that current thread is the UI thread.
      */
     private static void assertRunningOnUiThread() {
         assert Looper.getMainLooper().equals(Looper.myLooper());
     }
 }