Remove unnecessary Zygote class initialization activity when providers are absent (#1271)

Author: samtstern

auth/src/main/java/com/firebase/ui/auth/AuthUI.java

@@ -31,14 +31,13 @@
 
 import com.facebook.login.LoginManager;
 import com.firebase.ui.auth.data.model.FlowParameters;
-import com.firebase.ui.auth.data.remote.FacebookSignInHandler;
-import com.firebase.ui.auth.data.remote.TwitterSignInHandler;
 import com.firebase.ui.auth.ui.idp.AuthMethodPickerActivity;
 import com.firebase.ui.auth.util.CredentialUtils;
 import com.firebase.ui.auth.util.ExtraConstants;
 import com.firebase.ui.auth.util.GoogleApiUtils;
 import com.firebase.ui.auth.util.Preconditions;
 import com.firebase.ui.auth.util.data.PhoneNumberUtils;
+import com.firebase.ui.auth.util.data.ProviderAvailability;
 import com.firebase.ui.auth.util.data.ProviderUtils;
 import com.google.android.gms.auth.api.credentials.Credential;
 import com.google.android.gms.auth.api.credentials.CredentialRequest;
@@ -452,10 +451,10 @@ public Task<Void> then(@NonNull Task<Void> task) {
     }
 
     private Task<Void> signOutIdps(@NonNull Context context) {
-        if (FacebookSignInHandler.IS_AVAILABLE) {
+        if (ProviderAvailability.IS_FACEBOOK_AVAILABLE) {
             LoginManager.getInstance().logOut();
         }
-        if (TwitterSignInHandler.IS_AVAILABLE) {
+        if (ProviderAvailability.IS_TWITTER_AVAILABLE) {
             TwitterCore.getInstance().getSessionManager().clearActiveSession();
         }
         return GoogleSignIn.getClient(context, GoogleSignInOptions.DEFAULT_SIGN_IN).signOut();
@@ -874,7 +873,7 @@ public static final class FacebookBuilder extends Builder {
             public FacebookBuilder() {
                 //noinspection deprecation taking a hit for the backcompat team
                 super(FacebookAuthProvider.PROVIDER_ID);
-                if (!FacebookSignInHandler.IS_AVAILABLE) {
+                if (!ProviderAvailability.IS_FACEBOOK_AVAILABLE) {
                     throw new RuntimeException(
                             "Facebook provider cannot be configured " +
                                     "without dependency. Did you forget to add " +
@@ -912,7 +911,7 @@ public static final class TwitterBuilder extends Builder {
             public TwitterBuilder() {
                 //noinspection deprecation taking a hit for the backcompat team
                 super(TwitterAuthProvider.PROVIDER_ID);
-                if (!TwitterSignInHandler.IS_AVAILABLE) {
+                if (!ProviderAvailability.IS_TWITTER_AVAILABLE) {
                     throw new RuntimeException(
                             "Twitter provider cannot be configured " +
                                     "without dependency. Did you forget to add " +

auth/src/main/java/com/firebase/ui/auth/data/remote/FacebookSignInHandler.java

@@ -37,19 +37,6 @@
 
 @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
 public class FacebookSignInHandler extends ProviderSignInBase<AuthUI.IdpConfig> {
-    public static final boolean IS_AVAILABLE;
-
-    static {
-        boolean available;
-        try {
-            Class.forName("com.facebook.login.LoginManager");
-            available = true;
-        } catch (ClassNotFoundException e) {
-            available = false;
-        }
-        IS_AVAILABLE = available;
-    }
-
     private static final String EMAIL = "email";
     private static final String PUBLIC_PROFILE = "public_profile";
 

auth/src/main/java/com/firebase/ui/auth/data/remote/TwitterSignInHandler.java

@@ -16,6 +16,7 @@
 import com.firebase.ui.auth.data.model.Resource;
 import com.firebase.ui.auth.data.model.User;
 import com.firebase.ui.auth.ui.HelperActivityBase;
+import com.firebase.ui.auth.util.data.ProviderAvailability;
 import com.firebase.ui.auth.viewmodel.idp.ProviderSignInBase;
 import com.google.firebase.auth.TwitterAuthProvider;
 import com.twitter.sdk.android.core.Callback;
@@ -30,19 +31,8 @@
 
 @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
 public class TwitterSignInHandler extends ProviderSignInBase<Void> {
-    public static final boolean IS_AVAILABLE;
-
     static {
-        boolean available;
-        try {
-            Class.forName("com.twitter.sdk.android.core.identity.TwitterAuthClient");
-            available = true;
-        } catch (ClassNotFoundException e) {
-            available = false;
-        }
-        IS_AVAILABLE = available;
-
-        if (IS_AVAILABLE) {
+        if (ProviderAvailability.IS_TWITTER_AVAILABLE) {
             Context context = AuthUI.getApplicationContext();
             Twitter.initialize(new TwitterConfig.Builder(context)
                     .twitterAuthConfig(new TwitterAuthConfig(

auth/src/main/java/com/firebase/ui/auth/util/data/ProviderAvailability.java

@@ -0,0 +1,26 @@
+package com.firebase.ui.auth.util.data;
+
+import android.support.annotation.RestrictTo;
+
+@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
+public final class ProviderAvailability {
+    public static final boolean IS_FACEBOOK_AVAILABLE =
+            exists("com.facebook.login.LoginManager");
+    public static final boolean IS_TWITTER_AVAILABLE =
+            exists("com.twitter.sdk.android.core.identity.TwitterAuthClient");
+
+    private ProviderAvailability() {
+        throw new AssertionError("No instance for you!");
+    }
+
+    private static boolean exists(String name) {
+        boolean exists;
+        try {
+            Class.forName(name);
+            exists = true;
+        } catch (ClassNotFoundException e) {
+            exists = false;
+        }
+        return exists;
+    }
+}