[iOS][CredentialProvider] Show loading indicator for GCRSSOService APIs

Bug: 1156847
Change-Id: Ie15241942f1a22666ad2e9cf3a12927a8d18fc12
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2597401Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Commit-Queue: Javier Flores <javierrobles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838665}

ios/chrome/credential_provider_extension/BUILD.gn

@@ -64,6 +64,7 @@ ios_appex_bundle("credential_provider_extension") {
     ":password_util",
     ":reauthentication_handler",
     ":system_strings",
+    "//base",
     "//ios/chrome/common/app_group",
     "//ios/chrome/common/app_group:client",
     "//ios/chrome/common/credential_provider",

ios/chrome/credential_provider_extension/credential_provider_view_controller.mm

@@ -6,11 +6,13 @@
 
 #import <Foundation/Foundation.h>
 
+#include "base/check.h"
 #include "ios/chrome/common/app_group/app_group_constants.h"
 #include "ios/chrome/common/app_group/app_group_metrics.h"
 #import "ios/chrome/common/credential_provider/archivable_credential_store.h"
 #import "ios/chrome/common/credential_provider/constants.h"
 #import "ios/chrome/common/credential_provider/credential.h"
+#import "ios/chrome/common/ui/colors/semantic_color_names.h"
 #import "ios/chrome/common/ui/confirmation_alert/confirmation_alert_action_handler.h"
 #import "ios/chrome/common/ui/reauthentication/reauthentication_module.h"
 #import "ios/chrome/credential_provider_extension/account_verification_provider.h"
@@ -51,6 +53,9 @@
 // Interface for verified that accounts are still valid.
 @property(nonatomic, strong) AccountVerificationProvider* accountVerificator;
 
+// Loading indicator used for user validation, which APIs can take a long time.
+@property(nonatomic, strong) UIActivityIndicatorView* activityIndicatorView;
+
 @end
 
 @implementation CredentialProviderViewController
@@ -191,11 +196,36 @@
   [self exitWithErrorCode:ASExtensionErrorCodeCredentialIdentityNotFound];
 }
 
+// Shows a loading indicator,
+- (void)showLoadingIndicator {
+  DCHECK(!self.activityIndicatorView);
+  self.activityIndicatorView = [[UIActivityIndicatorView alloc] init];
+  UIActivityIndicatorView* activityView = self.activityIndicatorView;
+  activityView.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.view addSubview:activityView];
+  [NSLayoutConstraint activateConstraints:@[
+    [activityView.centerXAnchor
+        constraintEqualToAnchor:self.view.centerXAnchor],
+    [activityView.centerYAnchor
+        constraintEqualToAnchor:self.view.centerYAnchor],
+  ]];
+  [activityView startAnimating];
+  activityView.color = [UIColor colorNamed:kBlueColor];
+}
+
+// Hides the loading indicator.
+- (void)hideLoadingIndicator {
+  [self.activityIndicatorView removeFromSuperview];
+  self.activityIndicatorView = nil;
+}
+
 // Verifies that the user is still signed in.
 // Return NO in the completion when the user is no longer valid. YES otherwise.
 - (void)validateUserWithCompletion:(void (^)(BOOL))completion {
+  [self showLoadingIndicator];
   auto handler = ^(BOOL isValid) {
     dispatch_async(dispatch_get_main_queue(), ^{
+      [self hideLoadingIndicator];
       if (completion) {
         completion(isValid);
       }