Implement IntCachedFieldTrialParameter.

This allows caching int-typed field trial parameters for use
before native is loaded.

Bug: 1041865, 1012975
Change-Id: I9192d5fc7ee27dd617843e3afc5355d274d6e48f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2086255Reviewed-by: Xi Han <hanxi@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746850}

chrome/android/java/src/org/chromium/chrome/browser/flags/CachedFeatureFlags.java

@@ -116,6 +116,7 @@ public class CachedFeatureFlags {
 
     private static Map<String, Boolean> sBoolValuesReturned = new HashMap<>();
     private static Map<String, String> sStringValuesReturned = new HashMap<>();
+    private static Map<String, Integer> sIntValuesReturned = new HashMap<>();
     private static String sReachedCodeProfilerTrialGroup;
 
     /**
@@ -262,6 +263,17 @@ public class CachedFeatureFlags {
                 parameter.getSharedPreferenceKey(), parameter.getDefaultValue());
     }
 
+    /**
+     * TODO(crbug.com/1012975): Move this to IntCachedFieldTrialParameter when
+     * CachedFeatureFlags is in chrome/browser/flags.
+     *
+     * @return the value of the field trial parameter that should be used in this run.
+     */
+    public static int getValue(IntCachedFieldTrialParameter parameter) {
+        return getConsistentIntValue(
+                parameter.getSharedPreferenceKey(), parameter.getDefaultValue());
+    }
+
     private static void cacheStartSurfaceVariation() {
         String feature = ChromeFeatureList.getFieldTrialParamByFeature(
                 ChromeFeatureList.START_SURFACE_ANDROID, "start_surface_variation");
@@ -358,6 +370,15 @@ public class CachedFeatureFlags {
         return value;
     }
 
+    static int getConsistentIntValue(String preferenceName, int defaultValue) {
+        Integer value = sIntValuesReturned.get(preferenceName);
+        if (value == null) {
+            value = SharedPreferencesManager.getInstance().readInt(preferenceName, defaultValue);
+            sIntValuesReturned.put(preferenceName, value);
+        }
+        return value;
+    }
+
     private static String getPrefForFeatureFlag(String featureName) {
         String grandfatheredPrefKey = sNonDynamicPrefKeys.get(featureName);
         if (grandfatheredPrefKey == null) {
@@ -371,6 +392,7 @@ public class CachedFeatureFlags {
     public static void resetFlagsForTesting() {
         sBoolValuesReturned.clear();
         sStringValuesReturned.clear();
+        sIntValuesReturned.clear();
     }
 
     @VisibleForTesting

chrome/browser/flags/BUILD.gn

@@ -9,6 +9,7 @@ android_library("java") {
     "android/java/src/org/chromium/chrome/browser/flags/BooleanCachedFieldTrialParameter.java",
     "android/java/src/org/chromium/chrome/browser/flags/CachedFieldTrialParameter.java",
     "android/java/src/org/chromium/chrome/browser/flags/ChromeFeatureList.java",
+    "android/java/src/org/chromium/chrome/browser/flags/IntCachedFieldTrialParameter.java",
     "android/java/src/org/chromium/chrome/browser/flags/StringCachedFieldTrialParameter.java",
   ]
   deps = [

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/IntCachedFieldTrialParameter.java

+// Copyright 2020 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.flags;
+
+import org.chromium.chrome.browser.preferences.SharedPreferencesManager;
+
+/**
+ * An int-type {@link CachedFieldTrialParameter}.
+ */
+public class IntCachedFieldTrialParameter extends CachedFieldTrialParameter {
+    private int mDefaultValue;
+
+    public IntCachedFieldTrialParameter(
+            String featureName, String variationName, int defaultValue) {
+        super(featureName, variationName, FieldTrialParameterType.INT, null);
+        mDefaultValue = defaultValue;
+    }
+
+    public int getDefaultValue() {
+        return mDefaultValue;
+    }
+
+    @Override
+    void cacheToDisk() {
+        int value = ChromeFeatureList.getFieldTrialParamByFeatureAsInt(
+                getFeatureName(), getParameterName(), getDefaultValue());
+        SharedPreferencesManager.getInstance().writeInt(getSharedPreferenceKey(), value);
+    }
+}