Issue 5426 - ABP isn't packaged in the apk

mobile/android/base/java/org/mozilla/gecko/distribution/Distribution.java

Index: mobile/android/base/java/org/mozilla/gecko/distribution/Distribution.java
===================================================================
--- a/mobile/android/base/java/org/mozilla/gecko/distribution/Distribution.java
+++ b/mobile/android/base/java/org/mozilla/gecko/distribution/Distribution.java
@@ -444,17 +444,17 @@ public class Distribution {
         // Firefox for Android normally ignores application scope extensions,
         // and thus doesn't put the extensions directory in place. In Adblock
         // Browser however, we need this mechanism.
         //
         // This logic doesn't really belong here. However, here the change is
         // minimally invasive, and we're more likely to notice when the logic
         // changes for the distributions directory.
         try {
-            copyExtensionsFiles();
+            copyExtensionsFromPackagedAssets();
         } catch (IOException e) {
             Log.e(LOGTAG, "Error copying extensions files from APK.", e);
         }
 
         // Bail if we've already tried to initialize the distribution, and
         // there wasn't one.
         final SharedPreferences settings = getSharedPreferences();
 
@@ -766,41 +766,47 @@ public class Distribution {
         } finally {
             zip.close();
         }
 
         return distributionSet;
     }
 
     /**
-     * Copies the /extensions folder out of the APK and into the app's data directory.
-     * Adapted from copyFiles().
+     * Copies the /assets/extensions folder out of the APK and into the app's data directory.
+     * Adapted from copyFilesFromPackagedAssets().
      */
-    private void copyExtensionsFiles() throws IOException {
+    private void copyExtensionsFromPackagedAssets() throws IOException {
         final File applicationPackage = new File(packagePath);
         final ZipFile zip = new ZipFile(applicationPackage);
 
+        final String assetsPrefix = "assets/";
+        final String fullPrefix = assetsPrefix + "extensions/";
+
         try {
             final byte[] buffer = new byte[1024];
 
             final Enumeration<? extends ZipEntry> zipEntries = zip.entries();
             while (zipEntries.hasMoreElements()) {
                 final ZipEntry fileEntry = zipEntries.nextElement();
                 final String name = fileEntry.getName();
 
                 if (fileEntry.isDirectory()) {
                     // We'll let getDataFile deal with creating the directory hierarchy.
                     continue;
                 }
 
-                if (!name.startsWith("extensions/")) {
+                // Read from "assets/extensions/**".
+                if (!name.startsWith(fullPrefix)) {
                     continue;
                 }
 
-                final File outFile = getDataFile(name);
+                // Write to "extensions/**".
+                final String nameWithoutPrefix = name.substring(assetsPrefix.length());
+                final File outFile = getDataFile(nameWithoutPrefix);
                 if (outFile == null) {
                     continue;
                 }
 
                 final InputStream fileStream = zip.getInputStream(fileEntry);
                 try {
                     writeStream(fileStream, outFile, fileEntry.getTime(), buffer);
                 } finally {