Create KeyPrefix allowing dynamic SharedPreferences keys to be used.

SharedPreferencesManager now accepts dynamic keys as long as their
prefix was registered in ChromePreferenceKeys.

Bug: 1013781, 1022108
Change-Id: Ia5ed931d64fc5098dd4927c1794eede85b28e094
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929636Reviewed-by: Natalie Chouinard <chouinard@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719299}

chrome/browser/preferences/BUILD.gn

@@ -7,6 +7,7 @@ import("//build/config/android/rules.gni")
 android_library("java") {
   java_files = [
     "android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeys.java",
+    "android/java/src/org/chromium/chrome/browser/preferences/KeyPrefix.java",
     "android/java/src/org/chromium/chrome/browser/preferences/PrefChangeRegistrar.java",
     "android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java",
     "android/java/src/org/chromium/chrome/browser/preferences/SharedPreferencesManager.java",
@@ -34,7 +35,10 @@ java_cpp_enum("java_enums_srcjar") {
 
 android_library("javatests") {
   testonly = true
-  java_files = [ "android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeysTest.java" ]
+  java_files = [
+    "android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeysTest.java",
+    "android/java/src/org/chromium/chrome/browser/preferences/KeyPrefixTest.java",
+  ]
   deps = [
     ":java",
     "//base:base_java",

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeys.java

@@ -10,12 +10,12 @@ import java.util.Arrays;
 import java.util.List;
 
 /**
- * Contains String constants with the SharedPreferences keys used by Chrome.
+ * Contains String and {@link KeyPrefix} constants with the SharedPreferences keys used by Chrome.
  *
  * All Chrome layer SharedPreferences keys should be declared in this class.
  *
  * To add a new key:
- * 1. Declare it as a constant in this class. Its value should follow the format
+ * 1. Declare it as a String constant in this class. Its value should follow the format
  *    "Chrome.[Feature].[Key]"
  * 2. Add it to createKeysInUse().
  *
@@ -25,6 +25,17 @@ import java.util.List;
  * 3. If the key is in createGrandfatheredFormatKeysForTesting(), remove it from there.
  * 4. Delete the constant.
  *
+ * To add a new KeyPrefix:
+ * 1. Declare it as a KeyPrefix constant in this class. Its value should follow the format
+ *    "Chrome.[Feature].[KeyPrefix].*"
+ * 2. Add PREFIX_CONSTANT.pattern() to the list of used keys in
+ *    {@link ChromePreferenceKeys#createKeysInUse()} ()}.
+ *
+ * To deprecate a KeyPrefix that is not used anymore:
+ * 1. Add its String value to createDeprecatedKeysForTesting(), including the ".*"
+ * 2. Remove it from createKeysInUse().
+ * 3. Delete the KeyPrefix constant.
+ *
  * Tests in ChromePreferenceKeysTest ensure the sanity of this file.
  */
 public final class ChromePreferenceKeys {

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceKeysTest.java

@@ -113,7 +113,8 @@ public class ChromePreferenceKeysTest {
 
     private void doTestKeysConformToFormat(List<String> usedList, List<String> grandfathered) {
         Set<String> grandfatheredSet = new HashSet<>(grandfathered);
-        Pattern regex = Pattern.compile("Chrome.([A-Z][a-z0-9]+)+.([A-Z][a-z0-9]+)+");
+        String term = "([A-Z][a-z0-9]*)+";
+        Pattern regex = Pattern.compile("Chrome\\." + term + "\\." + term + "(\\.\\*)?");
 
         for (String keyInUse : usedList) {
             if (grandfatheredSet.contains(keyInUse)) {
@@ -128,12 +129,17 @@ public class ChromePreferenceKeysTest {
     // Below are tests to ensure that doTestKeysConformToFormat() works.
 
     private static class TestFormatConstantsClass {
-        public static final String GRANDFATHERED_IN = "grandfathered_in";
-        public static final String NEW1 = "Chrome.FeatureOne.Key1";
-        public static final String NEW2 = "Chrome.Foo.Key";
-        public static final String BROKEN_PREFIX = "Chrom.Foo.Key";
-        public static final String MISSING_FEATURE = "Chrome..Key";
-        public static final String LOWERCASE_KEY = "Chrome.Foo.key";
+        static final String GRANDFATHERED_IN = "grandfathered_in";
+        static final String NEW1 = "Chrome.FeatureOne.Key1";
+        static final String NEW2 = "Chrome.Foo.Key";
+        static final String BROKEN_PREFIX = "Chrom.Foo.Key";
+        static final String MISSING_FEATURE = "Chrome..Key";
+        static final String LOWERCASE_KEY = "Chrome.Foo.key";
+
+        static final KeyPrefix PREFIX = new KeyPrefix("Chrome.FeatureOne.KeyPrefix1.*");
+        static final KeyPrefix PREFIX_EXTRA_LEVEL =
+                new KeyPrefix("Chrome.FeatureOne.KeyPrefix1.ExtraLevel.*");
+        static final KeyPrefix PREFIX_MISSING_LEVEL = new KeyPrefix("Chrome.FeatureOne.*");
     }
 
     @Test
@@ -180,4 +186,27 @@ public class ChromePreferenceKeysTest {
                         TestFormatConstantsClass.NEW1, TestFormatConstantsClass.LOWERCASE_KEY),
                 Arrays.asList(TestFormatConstantsClass.GRANDFATHERED_IN));
     }
+
+    @Test
+    @SmallTest
+    public void testFormatCheck_prefixCorrect() {
+        doTestKeysConformToFormat(
+                Arrays.asList(TestFormatConstantsClass.PREFIX.pattern()), Collections.emptyList());
+    }
+
+    @Test(expected = AssertionError.class)
+    @SmallTest
+    public void testFormatCheck_prefixExtralevel() {
+        doTestKeysConformToFormat(
+                Arrays.asList(TestFormatConstantsClass.PREFIX_EXTRA_LEVEL.pattern()),
+                Collections.emptyList());
+    }
+
+    @Test(expected = AssertionError.class)
+    @SmallTest
+    public void testFormatCheck_prefixMissingLevel() {
+        doTestKeysConformToFormat(
+                Arrays.asList(TestFormatConstantsClass.PREFIX_MISSING_LEVEL.pattern()),
+                Collections.emptyList());
+    }
 }

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/KeyPrefix.java

+// Copyright 2019 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.chrome.browser.preferences;
+
+/**
+ * A prefix for a range of SharedPreferences keys generated dynamically.
+ *
+ * Instances should be declared as keys in {@link ChromePreferenceKeys}.
+ */
+public class KeyPrefix {
+    private final String mPrefix;
+
+    KeyPrefix(String pattern) {
+        // More thorough checking is performed in ChromePreferenceKeysTest.
+        assert pattern.endsWith(".*");
+        mPrefix = pattern.substring(0, pattern.length() - 1);
+    }
+
+    /**
+     * @param suffix A non-empty string. The '*' character is reserved.
+     * @return The complete SharedPreferences key to be passed to {@link SharedPreferencesManager}.
+     */
+    public String createKey(String suffix) {
+        return mPrefix + suffix;
+    }
+
+    String pattern() {
+        return mPrefix + "*";
+    }
+}

chrome/browser/preferences/android/java/src/org/chromium/chrome/browser/preferences/KeyPrefixTest.java

+// Copyright 2019 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.chrome.browser.preferences;
+
+import static org.junit.Assert.assertEquals;
+
+import android.support.test.filters.SmallTest;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
+
+/**
+ * Unit tests for {@link KeyPrefix}.
+ */
+@RunWith(ChromeJUnit4ClassRunner.class)
+public class KeyPrefixTest {
+    @Test
+    @SmallTest
+    public void testSuccess_validPattern() {
+        KeyPrefix prefix = new KeyPrefix("Chrome.Feature.KP.*");
+
+        assertEquals(prefix.pattern(), "Chrome.Feature.KP.*");
+        assertEquals(prefix.createKey("DynamicKey"), "Chrome.Feature.KP.DynamicKey");
+        assertEquals(prefix.createKey("Level.DynamicKey"), "Chrome.Feature.KP.Level.DynamicKey");
+    }
+
+    @Test(expected = AssertionError.class)
+    @SmallTest
+    public void testError_missingPeriod() {
+        new KeyPrefix("Chrome.Feature.KP");
+    }
+
+    @Test(expected = AssertionError.class)
+    @SmallTest
+    public void testError_missingStar() {
+        new KeyPrefix("Chrome.Feature.KP.");
+    }
+
+    @Test(expected = AssertionError.class)
+    @SmallTest
+    public void testError_extraStar() {
+        new KeyPrefix("Chrome.Feature.KP.**");
+    }
+}