Clean up other instances where Tab WindowAndroid was being set to null.

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 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.
 
 #include "content/browser/android/content_view_core_impl.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 249 matching lines @@
     Java_ContentViewCore_onNativeContentViewCoreDestroyed(
         env, j_obj, reinterpret_cast<intptr_t>(this));
   }
 }
 
 void ContentViewCoreImpl::UpdateWindowAndroid(
     JNIEnv* env,
     const base::android::JavaParamRef<jobject>& obj,
     jlong window_android) {
   ui::ViewAndroid* view = GetViewAndroid();
-  if (window_android) {
-    DCHECK(!GetWindowAndroid());
-    ui::WindowAndroid* window =
-        reinterpret_cast<ui::WindowAndroid*>(window_android);
-    window->AddChild(view);
-    for (auto& observer : observer_list_)
-      observer.OnAttachedToWindow();
-  } else {
+  ui::WindowAndroid* window =
+      reinterpret_cast<ui::WindowAndroid*>(window_android);
+  if (window == GetWindowAndroid())
+    return;
+  if (GetWindowAndroid()) {
     for (auto& observer : observer_list_)
       observer.OnDetachedFromWindow();
     view->RemoveFromParent();
   }
+  if (window) {
+    window->AddChild(view);
+    for (auto& observer : observer_list_)
+      observer.OnAttachedToWindow();
+  }
 }
 
 base::android::ScopedJavaLocalRef<jobject>
 ContentViewCoreImpl::GetWebContentsAndroid(JNIEnv* env,
                                            const JavaParamRef<jobject>& obj) {
   return web_contents_->GetJavaWebContents();
 }
 
 base::android::ScopedJavaLocalRef<jobject>
 ContentViewCoreImpl::GetJavaWindowAndroid(JNIEnv* env,
@@ skipping 1277 matching lines @@
     return ScopedJavaLocalRef<jobject>();
 
   return view->GetJavaObject();
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content