Moved InstalledAppProvider Android impl from content into chrome.

content/public/android/java/src/org/chromium/content/browser/installedapp/PackageHash.java

Index: content/public/android/java/src/org/chromium/content/browser/installedapp/PackageHash.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/installedapp/PackageHash.java b/content/public/android/java/src/org/chromium/content/browser/installedapp/PackageHash.java
deleted file mode 100644
index fbb4fb2001dc1897319d6976d253c96e1d6ef72f..0000000000000000000000000000000000000000
--- a/content/public/android/java/src/org/chromium/content/browser/installedapp/PackageHash.java
+++ /dev/null
@@ -1,98 +0,0 @@
-// Copyright 2017 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.installedapp;
-
-import org.chromium.base.VisibleForTesting;
-import org.chromium.content.browser.crypto.ByteArrayGenerator;
-
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
-import java.security.GeneralSecurityException;
-import java.security.InvalidKeyException;
-import java.security.Key;
-import java.security.NoSuchAlgorithmException;
-
-import javax.crypto.Mac;
-import javax.crypto.spec.SecretKeySpec;
-
-/**
- * Helper class for retrieving a device-unique hash for an Android package name.
- *
- * This is used to counter a potential timing attack against the getInstalledRelatedApps API, by
- * adding a pseudo-random time delay to the query. The delay is a hash of a globally unique
- * identifier for the current browser session, and the package name, which means websites are unable
- * to predict what each user's delay will be, nor compare between apps on a given device.
- *
- * The salt is generated per browser session (not per query, page load, user or device) because it
- * we want it to change "occasionally" -- not too frequently, but sometimes. Each time the salt
- * changes, it gives the site another opportunity to collect data that could be averaged out to
- * cancel out the random noise and find the true timing. So we don't want it changing too often.
- * However, it does need to change periodically: because installing or uninstalling the app creates
- * a noticeable change to the timing of the operation, we need to occasionally change the salt to
- * create plausible deniability (the attacker can't tell the difference between the salt changing
- * and the app being installed/uninstalled).
- */
-class PackageHash {
-    // Global salt string for the life of the browser process. A unique salt is generated for
-    // each run of the browser process that will be stable for its lifetime.
-    private static byte[] sSalt;
-
-    /**
-     * Returns a SHA-256 hash of the package name, truncated to a 16-bit integer.
-     */
-    public static short hashForPackage(String packageName) {
-        byte[] salt = getGlobalSalt();
-        Mac hasher;
-        try {
-            hasher = Mac.getInstance("HmacSHA256");
-        } catch (NoSuchAlgorithmException e) {
-            // Should never happen.
-            throw new RuntimeException(e);
-        }
-
-        byte[] packageNameBytes;
-        try {
-            packageNameBytes = packageName.getBytes("UTF-8");
-        } catch (UnsupportedEncodingException e) {
-            // Should never happen.
-            throw new RuntimeException(e);
-        }
-
-        Key key = new SecretKeySpec(salt, "HmacSHA256");
-        try {
-            hasher.init(key);
-        } catch (InvalidKeyException e) {
-            // Should never happen.
-            throw new RuntimeException(e);
-        }
-        byte[] digest = hasher.doFinal(packageNameBytes);
-        // Take just the first two bytes of the digest.
-        int hash = ((((int) digest[0]) & 0xff) << 8) | (((int) digest[1]) & 0xff);
-        return (short) hash;
-    }
-
-    /**
-     * Gets the global salt for the current browser session.
-     *
-     * If one does not exist, generates one using a PRNG and caches it, then returns it.
-     */
-    private static byte[] getGlobalSalt() {
-        if (sSalt == null) {
-            try {
-                sSalt = new ByteArrayGenerator().getBytes(20);
-            } catch (IOException | GeneralSecurityException e) {
-                // If this happens, the crypto source is messed up and we want the browser to crash.
-                throw new RuntimeException(e);
-            }
-        }
-
-        return sSalt;
-    }
-
-    @VisibleForTesting
-    public static void setGlobalSaltForTesting(byte[] salt) {
-        sSalt = salt;
-    }
-}