Add PolicyCache class

Add getter function of PolicyCache that reads from the SharedPreferences
https://source.chromium.org/chromium/chromium/src/+/master:components/policy/core/common/policy_service_impl.cc;l=146?q=IDS_POLICY_MIGRATED_NEW_POLICY&ss=chromium%2Fchromium%2Fsrc

Bug: 1127469
Change-Id: If6f8103e55625439a0607e358449ffddfe2949cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633927
Commit-Queue: Owen Min <zmin@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845143}

components/policy/android/BUILD.gn

@@ -30,6 +30,7 @@ android_library("policy_java") {
   sources = _jni_sources + [
               "java/src/org/chromium/components/policy/AbstractAppRestrictionsProvider.java",
               "java/src/org/chromium/components/policy/AppRestrictionsProvider.java",
+              "java/src/org/chromium/components/policy/PolicyCache.java",
               "java/src/org/chromium/components/policy/PolicyProvider.java",
             ]
 }
@@ -61,6 +62,7 @@ java_library("components_policy_junit_tests") {
   sources = [
     "junit/src/org/chromium/components/policy/AbstractAppRestrictionsProviderTest.java",
     "junit/src/org/chromium/components/policy/CombinedPolicyProviderTest.java",
+    "junit/src/org/chromium/components/policy/PolicyCacheTest.java",
     "junit/src/org/chromium/components/policy/PolicyConverterTest.java",
     "junit/src/org/chromium/components/policy/test/annotations/PoliciesTest.java",
   ]

components/policy/android/java/src/org/chromium/components/policy/PolicyCache.java

+// Copyright 2021 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.components.policy;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.annotation.VisibleForTesting;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import org.chromium.base.ContextUtils;
+
+/**
+ * Manage policy cache that will be used during browser launch stage.
+ *
+ * Policy loading is async on Android and caching policy values makes them
+ * available during launch stage even before native library is ready.
+ */
+public class PolicyCache {
+    @VisibleForTesting
+    static final String POLICY_PREF = "Components.Policy";
+
+    private static SharedPreferences sSharedPreferences;
+
+    /**
+     * Creates and returns SharedPreferences instance that is used to cache policy
+     * value.
+     *
+     * @return The SharedPreferences instance that is used for policy caching. Returns null if
+     *         application context is not available.
+     */
+    private static SharedPreferences getSharedPreferences() {
+        if (sSharedPreferences == null) {
+            Context context = ContextUtils.getApplicationContext();
+            // Policy cache is not accessiable without application context.
+            if (context == null) return null;
+            sSharedPreferences = context.getSharedPreferences(POLICY_PREF, Context.MODE_PRIVATE);
+        }
+        return sSharedPreferences;
+    }
+
+    /**
+     * @param policy The name of policy.
+     * @return The value of cached integer policy, null if there is no valid
+     * cached policy.
+     */
+    public static Integer getIntValue(String policy) {
+        SharedPreferences sSharedPreferences = getSharedPreferences();
+        if (sSharedPreferences == null) return null;
+        if (!sSharedPreferences.contains(policy)) return null;
+        return sSharedPreferences.getInt(policy, 0);
+    }
+
+    /**
+     * @param policy The name of policy.
+     * @return The value of cached boolean policy, null if there is no valid
+     * cached policy.
+     */
+    public static Boolean getBooleanValue(String policy) {
+        SharedPreferences sSharedPreferences = getSharedPreferences();
+        if (sSharedPreferences == null) return null;
+        if (!sSharedPreferences.contains(policy)) return null;
+        return sSharedPreferences.getBoolean(policy, false);
+    }
+
+    /**
+     * @param policy The name of policy.
+     * @return The value of cached string policy, null if there is no valid
+     * cached policy.
+     */
+    public static String getStringValue(String policy) {
+        SharedPreferences sSharedPreferences = getSharedPreferences();
+        if (sSharedPreferences == null) return null;
+        if (!sSharedPreferences.contains(policy)) return null;
+        return sSharedPreferences.getString(policy, null);
+    }
+
+    /**
+     * @param policy The name of policy.
+     * @return The value of cached list policy, null if there is no valid
+     * cached policy.
+     */
+    public static JSONArray getListValue(String policy) {
+        SharedPreferences sSharedPreferences = getSharedPreferences();
+        if (sSharedPreferences == null) return null;
+        if (!sSharedPreferences.contains(policy)) return null;
+        try {
+            return new JSONArray(sSharedPreferences.getString(policy, null));
+        } catch (JSONException e) {
+            return null;
+        }
+    }
+
+    /**
+     * @param policy The name of policy.
+     * @return The value of cached dictionary policy, null if there is no valid
+     * cached policy.
+     */
+    public static JSONObject getDictValue(String policy) {
+        SharedPreferences sSharedPreferences = getSharedPreferences();
+        if (sSharedPreferences == null) return null;
+        if (!sSharedPreferences.contains(policy)) return null;
+        try {
+            return new JSONObject(sSharedPreferences.getString(policy, null));
+        } catch (JSONException e) {
+            return null;
+        }
+    }
+
+    @VisibleForTesting
+    static void resetSharedPreferencesForTests() {
+        sSharedPreferences = null;
+    }
+}

components/policy/android/junit/src/org/chromium/components/policy/PolicyCacheTest.java

+// Copyright 2021 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.components.policy;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.annotation.Config;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.test.BaseRobolectricTestRunner;
+
+/** Robolectric test for PolicyCache.  */
+@RunWith(BaseRobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public final class PolicyCacheTest {
+    private static final String POLICY_NAME = "policy-name";
+
+    private SharedPreferences mSharedPreferences;
+
+    @Before
+    public void setUp() {
+        mSharedPreferences = ContextUtils.getApplicationContext().getSharedPreferences(
+                PolicyCache.POLICY_PREF, Context.MODE_PRIVATE);
+        PolicyCache.resetSharedPreferencesForTests();
+    }
+
+    @After
+    public void tearDown() {}
+
+    @Test
+    public void testGetInt() {
+        Assert.assertNull(PolicyCache.getIntValue(POLICY_NAME));
+        int expectedPolicyValue = 42;
+        mSharedPreferences.edit().putInt(POLICY_NAME, expectedPolicyValue).apply();
+        Assert.assertEquals(expectedPolicyValue, PolicyCache.getIntValue(POLICY_NAME).intValue());
+    }
+
+    @Test
+    public void testGetBoolean() {
+        Assert.assertNull(PolicyCache.getBooleanValue(POLICY_NAME));
+        boolean expectedPolicyValue = true;
+        mSharedPreferences.edit().putBoolean(POLICY_NAME, expectedPolicyValue).apply();
+        Assert.assertEquals(
+                expectedPolicyValue, PolicyCache.getBooleanValue(POLICY_NAME).booleanValue());
+    }
+
+    @Test
+    public void testGetString() {
+        Assert.assertNull(PolicyCache.getStringValue(POLICY_NAME));
+        String expectedPolicyValue = "test-value";
+        mSharedPreferences.edit().putString(POLICY_NAME, expectedPolicyValue).apply();
+        Assert.assertEquals(expectedPolicyValue, PolicyCache.getStringValue(POLICY_NAME));
+    }
+
+    @Test
+    public void testGetList() throws JSONException {
+        Assert.assertNull(PolicyCache.getListValue(POLICY_NAME));
+        String policyValue = "[42, \"test\", true]";
+        mSharedPreferences.edit().putString(POLICY_NAME, policyValue).apply();
+        JSONArray actualPolicyValue = PolicyCache.getListValue(POLICY_NAME);
+        Assert.assertNotNull(actualPolicyValue);
+        Assert.assertEquals(3, actualPolicyValue.length());
+        Assert.assertEquals(42, actualPolicyValue.getInt(0));
+        Assert.assertEquals("test", actualPolicyValue.getString(1));
+        Assert.assertEquals(true, actualPolicyValue.getBoolean(2));
+    }
+
+    @Test
+    public void testGetInvalidList() throws JSONException {
+        String policyValue = "[42, \"test\"";
+        mSharedPreferences.edit().putString(POLICY_NAME, policyValue).apply();
+        Assert.assertNull(PolicyCache.getListValue(POLICY_NAME));
+    }
+
+    @Test
+    public void testGetDict() throws JSONException {
+        Assert.assertNull(PolicyCache.getDictValue(POLICY_NAME));
+        String policyValue = "{\"key1\":\"value1\", \"key2\":{\"a\":1, \"b\":2}}";
+        mSharedPreferences.edit().putString(POLICY_NAME, policyValue).apply();
+        JSONObject actualPolicyValue = PolicyCache.getDictValue(POLICY_NAME);
+        Assert.assertNotNull(actualPolicyValue);
+        Assert.assertEquals(2, actualPolicyValue.length());
+        Assert.assertEquals("value1", actualPolicyValue.getString("key1"));
+        Assert.assertEquals(1, actualPolicyValue.getJSONObject("key2").getInt("a"));
+        Assert.assertEquals(2, actualPolicyValue.getJSONObject("key2").getInt("b"));
+    }
+
+    @Test
+    public void testGetInvalidDict() throws JSONException {
+        Assert.assertNull(PolicyCache.getDictValue(POLICY_NAME));
+        String policyValue = "{\"key1\":\"value1\", \"key2\":{\"a\":1, \"b\":2}";
+        mSharedPreferences.edit().putString(POLICY_NAME, policyValue).apply();
+        Assert.assertNull(PolicyCache.getListValue(POLICY_NAME));
+    }
+}