Bug 30605: Honor privacy.spoof_english in Android

This checks `privacy.spoof_english` whenever `setLocales` is
called from Fenix side and sets `intl.accept_languages`
accordingly.

Bug 40198: Expose privacy.spoof_english pref in GeckoView

mobile/android/geckoview/api.txt

@@ -886,6 +886,7 @@ package org.mozilla.geckoview {
     method public boolean getRemoteDebuggingEnabled();
     method @Nullable public GeckoRuntime getRuntime();
     method @Nullable public Rect getScreenSizeOverride();
+    method public boolean getSpoofEnglish();
     method public boolean getTranslationsOfferPopup();
     method @NonNull public String getTrustedRecursiveResolverUri();
     method public int getTrustedRecusiveResolverMode();
@@ -915,6 +916,7 @@ package org.mozilla.geckoview {
     method @NonNull public GeckoRuntimeSettings setLoginAutofillEnabled(boolean);
     method @NonNull public GeckoRuntimeSettings setPreferredColorScheme(int);
     method @NonNull public GeckoRuntimeSettings setRemoteDebuggingEnabled(boolean);
+    method @NonNull public GeckoRuntimeSettings setSpoofEnglish(boolean);
     method @NonNull public GeckoRuntimeSettings setTranslationsOfferPopup(boolean);
     method @NonNull public GeckoRuntimeSettings setTrustedRecursiveResolverMode(int);
     method @NonNull public GeckoRuntimeSettings setTrustedRecursiveResolverUri(@NonNull String);
@@ -968,6 +970,7 @@ package org.mozilla.geckoview {
     method @NonNull public GeckoRuntimeSettings.Builder preferredColorScheme(int);
     method @NonNull public GeckoRuntimeSettings.Builder remoteDebuggingEnabled(boolean);
     method @NonNull public GeckoRuntimeSettings.Builder screenSizeOverride(int, int);
+    method @NonNull public GeckoRuntimeSettings.Builder spoofEnglish(boolean);
     method @NonNull public GeckoRuntimeSettings.Builder translationsOfferPopup(boolean);
     method @NonNull public GeckoRuntimeSettings.Builder trustedRecursiveResolverMode(int);
     method @NonNull public GeckoRuntimeSettings.Builder trustedRecursiveResolverUri(@NonNull String);

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntimeSettings.java

@@ -565,6 +565,17 @@ public final class GeckoRuntimeSettings extends RuntimeSettings {
       getSettings().setLargeKeepaliveFactor(factor);
       return this;
     }
+
+    /**
+     * Sets whether we should spoof locale to English for webpages.
+     *
+     * @param flag True if we should spoof locale to English for webpages, false otherwise.
+     * @return This Builder instance.
+     */
+    public @NonNull Builder spoofEnglish(final boolean flag) {
+      getSettings().mSpoofEnglish.set(flag ? 2 : 1);
+      return this;
+    }
   }
 
   private GeckoRuntime mRuntime;
@@ -634,6 +645,7 @@ public final class GeckoRuntimeSettings extends RuntimeSettings {
       new Pref<Boolean>("privacy.globalprivacycontrol.pbmode.enabled", true);
   /* package */ final Pref<Boolean> mGlobalPrivacyControlFunctionalityEnabled =
       new Pref<Boolean>("privacy.globalprivacycontrol.functionality.enabled", true);
+  /* package */ final Pref<Integer> mSpoofEnglish = new Pref<>("privacy.spoof_english", 0);
 
   /* package */ int mPreferredColorScheme = COLOR_SCHEME_SYSTEM;
 
@@ -1625,6 +1637,26 @@ public final class GeckoRuntimeSettings extends RuntimeSettings {
     return this;
   }
 
+  /**
+   * Get whether we should spoof locale to English for webpages.
+   *
+   * @return Whether we should spoof locale to English for webpages.
+   */
+  public boolean getSpoofEnglish() {
+    return mSpoofEnglish.get() == 2;
+  }
+
+  /**
+   * Set whether we should spoof locale to English for webpages.
+   *
+   * @param flag A flag determining whether we should locale to English for webpages.
+   * @return This GeckoRuntimeSettings instance.
+   */
+  public @NonNull GeckoRuntimeSettings setSpoofEnglish(final boolean flag) {
+    mSpoofEnglish.commit(flag ? 2 : 1);
+    return this;
+  }
+
   @Override // Parcelable
   public void writeToParcel(final Parcel out, final int flags) {
     super.writeToParcel(out, flags);

mobile/shared/components/geckoview/GeckoViewStartup.sys.mjs

@@ -11,6 +11,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
   ActorManagerParent: "resource://gre/modules/ActorManagerParent.sys.mjs",
   EventDispatcher: "resource://gre/modules/Messaging.sys.mjs",
   PdfJs: "resource://pdf.js/PdfJs.sys.mjs",
+  RFPHelper: "resource://gre/modules/RFPHelper.sys.mjs",
 });
 
 const { debug, warn } = GeckoViewUtils.initLogging("Startup");
@@ -339,6 +340,10 @@ export class GeckoViewStartup {
         if (aData.requestedLocales) {
           Services.locale.requestedLocales = aData.requestedLocales;
         }
+        lazy.RFPHelper._handleSpoofEnglishChanged();
+        if (Services.prefs.getIntPref("privacy.spoof_english", 0) === 2) {
+          break;
+        }
         const pls = Cc["@mozilla.org/pref-localizedstring;1"].createInstance(
           Ci.nsIPrefLocalizedString
         );