Add MainSettingsFragmentTest

MainSettings.java have bit less test coverage over some of the
preferences, for example, the HomepageSettings at this moment. Adding
MainSettingsFragmentTest is aiming for more test coverage for the
list of preferences on the settings screen.

Bug: 1052060, 1066362
Change-Id: Ib51c133f2a73f4ec85cc185c4101833bc3fa0b58
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2124729
Commit-Queue: Wenyu Fu <wenyufu@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Reviewed-by: Natalie Chouinard <chouinard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754957}

chrome/android/chrome_test_java_sources.gni

@@ -428,6 +428,7 @@ chrome_test_java_sources = [
   "javatests/src/org/chromium/chrome/browser/searchwidget/SearchActivityTest.java",
   "javatests/src/org/chromium/chrome/browser/searchwidget/SearchWidgetProviderTest.java",
   "javatests/src/org/chromium/chrome/browser/services/GoogleServicesManagerIntegrationTest.java",
+  "javatests/src/org/chromium/chrome/browser/settings/MainSettingsFragmentTest.java",
   "javatests/src/org/chromium/chrome/browser/settings/SettingsActivityTest.java",
   "javatests/src/org/chromium/chrome/browser/settings/homepage/HomepageSettingsFragmentTest.java",
   "javatests/src/org/chromium/chrome/browser/settings/homepage/HomepageSettingsFragmentWithEditorTest.java",

chrome/android/java/src/org/chromium/chrome/browser/settings/MainSettings.java

@@ -56,7 +56,6 @@ public class MainSettings extends PreferenceFragmentCompat
     public static final String PREF_UI_THEME = "ui_theme";
     public static final String PREF_DATA_REDUCTION = "data_reduction";
     public static final String PREF_NOTIFICATIONS = "notifications";
-    public static final String PREF_LANGUAGES = "languages";
     public static final String PREF_DOWNLOADS = "downloads";
     public static final String PREF_DEVELOPER = "developer";
 

chrome/android/java/src/org/chromium/chrome/browser/tracing/settings/DeveloperSettings.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.tracing.settings;
 
 import android.os.Bundle;
 
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.PreferenceFragmentCompat;
 
 import org.chromium.chrome.R;
@@ -25,9 +26,13 @@ public class DeveloperSettings extends PreferenceFragmentCompat {
     // Non-translated strings:
     private static final String MSG_DEVELOPER_OPTIONS_TITLE = "Developer options";
 
+    private static Boolean sIsEnabledForTests;
+
     public static boolean shouldShowDeveloperSettings() {
         // Always enabled on canary, dev and local builds, otherwise can be enabled by tapping the
         // Chrome version in Settings>About multiple times.
+        if (sIsEnabledForTests != null) return sIsEnabledForTests;
+
         if (VersionConstants.CHANNEL <= Channel.DEV) return true;
         return SharedPreferencesManager.getInstance().readBoolean(
                 ChromePreferenceKeys.SETTINGS_DEVELOPER_ENABLED, false);
@@ -38,6 +43,11 @@ public class DeveloperSettings extends PreferenceFragmentCompat {
                 ChromePreferenceKeys.SETTINGS_DEVELOPER_ENABLED, true);
     }
 
+    @VisibleForTesting
+    public static void setIsEnabledForTests(Boolean isEnabled) {
+        sIsEnabledForTests = isEnabled;
+    }
+
     @Override
     public void onCreatePreferences(Bundle savedInstanceState, String s) {
         getActivity().setTitle(MSG_DEVELOPER_OPTIONS_TITLE);