Add tab reparenting

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index d70219a71ef275a274ba0f2cb91ad79fe20f34a8..bb640db81fd44b80bd434c3553a0ed84b956ae28 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -273,6 +273,23 @@ ContentViewCoreImpl::~ContentViewCoreImpl() {
   }
 }
 
+void ContentViewCoreImpl::UpdateWindowAndroid(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& obj,
+    jlong window_android) {
+  if (window_android) {

[no sievers, 2016/02/25 19:23:16]

What about |window_android_ != null|?

If that is not supposed to happen, can you DCHECK?
Otherwise we might still want to notify OnDetachedFromWindow() first.

[Yusuf, 2016/02/25 19:37:03]

Good point. I would rather DCHECK. Whoever uses this call should be setting it
to null first on the old activity.

+    window_android_ = reinterpret_cast<ui::WindowAndroid*>(window_android);
+    FOR_EACH_OBSERVER(ContentViewCoreImplObserver,
+                      observer_list_,
+                      OnAttachedToWindow());
+  } else {
+    FOR_EACH_OBSERVER(ContentViewCoreImplObserver,
+                      observer_list_,
+                      OnDetachedFromWindow());
+    window_android_ = NULL;
+  }
+}
+
 base::android::ScopedJavaLocalRef<jobject>
 ContentViewCoreImpl::GetWebContentsAndroid(JNIEnv* env,
                                            const JavaParamRef<jobject>& obj) {