Don't try to enable saving password in EG tests

The password settings EG tests currently try to enable saving passwords in
PrefService. This is not necesary, because saving passwords is enabled by
default (see PasswordManager::RegisterProfilePrefs).

It is also harmful, because it:
(1) Won't catch if the default setting being "enabled" regresses, or some other
    tests start failing to clean-up.
(2) Increases the complexity of the code.

Therefore, this CL removes the code which enables the password setting in the
passwords settings EG tests.

Bug: 744058
Change-Id: I315935319cbaacb871ba6214b832c04902afffa9
Reviewed-on: https://chromium-review.googlesource.com/572903Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487109}

ios/chrome/browser/ui/settings/passwords_settings_egtest.mm

@@ -12,10 +12,7 @@
 #include "components/autofill/core/common/password_form.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/password_manager/core/browser/password_store.h"
-#include "components/password_manager/core/common/password_manager_pref_names.h"
-#include "components/prefs/pref_service.h"
 #include "components/strings/grit/components_strings.h"
-#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/passwords/ios_chrome_password_store_factory.h"
 #import "ios/chrome/browser/ui/settings/password_details_collection_view_controller_for_testing.h"
 #import "ios/chrome/browser/ui/settings/reauthentication_module.h"
@@ -276,32 +273,15 @@ MockReauthenticationModule* SetUpAndReturnMockReauthenticationModule() {
   [super tearDown];
 }
 
-// Return pref for saving passwords back to the passed value and restores the
-// experimental flag for viewing passwords.
-- (void)passwordsTearDown:(BOOL)defaultPasswordManagementSetting
-                         :(NSString*)oldExperiment {
-  ios::ChromeBrowserState* browserState =
-      chrome_test_util::GetOriginalBrowserState();
-  PrefService* preferences = browserState->GetPrefs();
-  preferences->SetBoolean(
-      password_manager::prefs::kPasswordManagerSavingEnabled,
-      defaultPasswordManagementSetting);
-
+// Restores the experimental flag for viewing passwords.
+- (void)passwordsTearDown:(NSString*)oldExperiment {
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   [defaults setObject:oldExperiment forKey:@"EnableViewCopyPasswords"];
 }
 
-// Sets the preference to allow saving passwords and activates the flag to use
-// the new UI for viewing passwords in settings. Also, ensures that original
-// state is restored after the test ends.
+// Activates the flag to use the new UI for viewing passwords in settings.
+// Also, ensures that original state is restored after the test ends.
 - (void)scopedEnablePasswordManagementAndViewingUI {
-  // Retrieve the original preference state.
-  ios::ChromeBrowserState* browserState =
-      chrome_test_util::GetOriginalBrowserState();
-  PrefService* preferences = browserState->GetPrefs();
-  bool defaultPasswordManagerSavingPref = preferences->GetBoolean(
-      password_manager::prefs::kPasswordManagerSavingEnabled);
-
   // Retrieve the experiment setting.
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   NSString* oldSetting = [defaults stringForKey:@"EnableViewCopyPasswords"];
@@ -309,13 +289,9 @@ MockReauthenticationModule* SetUpAndReturnMockReauthenticationModule() {
   // Ensure restoring that on tear-down.
   __weak PasswordsSettingsTestCase* weakSelf = self;
   [self setTearDownHandler:^{
-    [weakSelf passwordsTearDown:defaultPasswordManagerSavingPref:oldSetting];
+    [weakSelf passwordsTearDown:oldSetting];
   }];
 
-  // Enable saving.
-  preferences->SetBoolean(
-      password_manager::prefs::kPasswordManagerSavingEnabled, true);
-
   // Enable viewing passwords in settings.
   [defaults setObject:@"Enabled" forKey:@"EnableViewCopyPasswords"];
 }