Attempt 3 at a better touch tabstrip. There is still a bunch to do,

ui/views/view_model.cc

Index: ui/views/view_model.cc
diff --git a/ui/views/view_model.cc b/ui/views/view_model.cc
index 8ce247434cfc02442b56e7f5987fe36480280ec0..0f18ad5ca281f32bb5662a8526b57d4c29c45e15 100644
--- a/ui/views/view_model.cc
+++ b/ui/views/view_model.cc
@@ -17,6 +17,8 @@ ViewModel::~ViewModel() {
 }
 
 void ViewModel::Add(View* view, int index) {
+  DCHECK_LE(index, static_cast<int>(entries_.size()));
+  DCHECK_GE(index, 0);
   Entry entry;
   entry.view = view;
   entries_.insert(entries_.begin() + index, entry);
@@ -26,6 +28,7 @@ void ViewModel::Remove(int index) {
   if (index == -1)
     return;
 
+  check_index(index);
   entries_.erase(entries_.begin() + index);
 }