Ensure //ios/web_view sign in state is cleared on start up.

In the combined CronetChromeWebView framework, Cronet may be started
first, resulting in ignored command line flags set in
web_view_global_state_util.mm.

Change-Id: I1b65558d9042d726f634a87ac5ea1e1bd8df0a9c
Reviewed-on: https://chromium-review.googlesource.com/c/1290193Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Commit-Queue: John Wu <jzw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601000}

ios/web_view/internal/signin/web_view_signin_manager_factory.mm

@@ -11,6 +11,7 @@
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
 #include "components/signin/core/browser/profile_management_switches.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/signin/core/browser/signin_pref_names.h"
@@ -69,6 +70,14 @@ WebViewSigninManagerFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   WebViewBrowserState* browser_state =
       WebViewBrowserState::FromBrowserState(context);
+
+  // Clearing the sign in state on start up greatly simplifies the management of
+  // ChromeWebView's signin state.
+  PrefService* pref_service = browser_state->GetPrefs();
+  pref_service->ClearPref(prefs::kGoogleServicesAccountId);
+  pref_service->ClearPref(prefs::kGoogleServicesUsername);
+  pref_service->ClearPref(prefs::kGoogleServicesUserAccountId);
+
   std::unique_ptr<SigninManager> service = std::make_unique<SigninManager>(
       WebViewSigninClientFactory::GetForBrowserState(browser_state),
       WebViewOAuth2TokenServiceFactory::GetForBrowserState(browser_state),

ios/web_view/internal/web_view_global_state_util.mm

@@ -29,13 +29,6 @@ void InitializeGlobalState() {
     web_main_delegate =
         std::make_unique<ios_web_view::WebViewWebMainDelegate>();
     web::WebMainParams params(web_main_delegate.get());
-    params.argc = 2;
-    const char* executable = "ios-web-view";
-    // This is used in SigninManagerBase to clear the tokens on startup. This
-    // greatly simplifies the management of ChromeWebView's signin state.
-    const char* clear_token = "--clear-token-service";
-    const char* argv[] = {executable, clear_token};
-    params.argv = argv;
     web_main = std::make_unique<web::WebMain>(std::move(params));
   });
 }