Refined DCHECK preventing multiple event forwarders in VA tree path

ui/android/view_android.cc

Index: ui/android/view_android.cc
diff --git a/ui/android/view_android.cc b/ui/android/view_android.cc
index 15e51a0042ca48b6eb5c29d0bbbc6cafdb9541a3..855c0ce34d4b08639768b4f04f3bf19804177d29 100644
--- a/ui/android/view_android.cc
+++ b/ui/android/view_android.cc
@@ -115,7 +115,8 @@ void ViewAndroid::AddChild(ViewAndroid* child) {
   DCHECK(child);
   DCHECK(std::find(children_.begin(), children_.end(), child) ==
          children_.end());
-  DCHECK(!SubtreeHasEventForwarder(child) || !ViewTreeHasEventForwarder(this))
+  DCHECK(GetWindowAndroid() == this || !SubtreeHasEventForwarder(child) ||
+         !ViewTreeHasEventForwarder(this))

[boliu, 2017/05/08 16:54:55]

the previous check is too strict. check should be there's at most one forwarder
from node to root path, but previous code is checking there's only one forwarder
in the entire tree

but I have no idea what this new check does now

[Jinsuk Kim, 2017/05/10 01:42:10]

Updated the DCHECK to do what's actually intended.

       << "Only one event handler is allowed.";
 
   // The new child goes to the top, which is the end of the list.