Re-enable JSWindowIDManagerTest.WindowID

ios/web/web_state/js/crw_js_window_id_manager_unittest.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/web_state/js/crw_js_window_id_manager.h"
 
 #include "base/mac/scoped_nsobject.h"
 #import "ios/web/public/test/crw_test_js_injection_receiver.h"
+#import "ios/web/public/test/js_test_util.h"
 #include "ios/web/public/web_client.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
 namespace {
 
 class JSWindowIDManagerTest : public PlatformTest {
  protected:
   void SetUp() override {
     PlatformTest::SetUp();
     receiver_.reset([[CRWTestJSInjectionReceiver alloc] init]);
     manager_.reset([[CRWJSWindowIdManager alloc] initWithReceiver:receiver_]);
     web::SetWebClient(&web_client_);
   }
   void TearDown() override {
     web::SetWebClient(nullptr);
     PlatformTest::TearDown();
   }
   // Required for CRWJSWindowIdManager creation.
   base::scoped_nsobject<CRWTestJSInjectionReceiver> receiver_;
   // Testable CRWJSWindowIdManager.
   base::scoped_nsobject<CRWJSWindowIdManager> manager_;
   // WebClient required for getting early page script, which must be injected
   // before CRWJSWindowIdManager.
   web::WebClient web_client_;
 };
 
-// TODO(jyquinn): enable this test (crbug.com/465898).
-TEST_F(JSWindowIDManagerTest, DISABLED_WindowID) {
+// Tests that reinjection of window ID JS results in a different window ID.
+// TODO(ios): This test only works for the current implementation using
+// UIWebView. CRWTestJSInjectionReceiver should be re-written to eliminate
+// web view specificity (crbug.com/486840).
+TEST_F(JSWindowIDManagerTest, WindowIDReinjection) {
   EXPECT_TRUE(manager_.get());
   [manager_ inject];
   NSString* windowID = [manager_ windowId];
   EXPECT_EQ(32U, [windowID length]);
+  // Reset the __gCrWeb object to enable reinjection.
+  web::EvaluateJavaScriptAsString(manager_, @"__gCrWeb = undefined;");
   // Inject a second time to check that the ID is different.
   [manager_ inject];
   NSString* windowID2 = [manager_ windowId];
   EXPECT_FALSE([windowID isEqualToString:windowID2]);
 }
 
-TEST_F(JSWindowIDManagerTest, WindowIDDifferent) {
+// Tests that window ID injection by a second manager results in a different
+// window ID.
+TEST_F(JSWindowIDManagerTest, WindowIDDifferentManager) {
   [manager_ inject];
   NSString* windowID = [manager_ windowId];
   base::scoped_nsobject<CRWTestJSInjectionReceiver> receiver2(
       [[CRWTestJSInjectionReceiver alloc] init]);
   base::scoped_nsobject<CRWJSWindowIdManager> manager2(
       [[CRWJSWindowIdManager alloc] initWithReceiver:receiver2]);
   [manager2 inject];
   NSString* windowID2 = [manager2 windowId];
   EXPECT_NSNE(windowID, windowID2);
 }
 
 }  // namespace