[pdf] Allow invalidation during paint.

pdf/paint_manager.cc

Index: pdf/paint_manager.cc
diff --git a/pdf/paint_manager.cc b/pdf/paint_manager.cc
index ea9cc7814679f0c077ce1e0861a83fab2d4fef93..28406d904f4b6d04794e24fc2954a58ff8ec1079 100644
--- a/pdf/paint_manager.cc
+++ b/pdf/paint_manager.cc
@@ -141,8 +141,9 @@ void PaintManager::Invalidate() {
 }
 
 void PaintManager::InvalidateRect(const pp::Rect& rect) {
-  DCHECK(!in_paint_);
-
+  // Note, we can't DCHECK(!in_paint_) here because javascript inside the

[Tom Sepez, 2017/01/19 17:43:37]

Do we just want to no-op it in this special case?  Continuing might re-enter
things that weren't expecting it ...

[dsinclair, 2017/01/19 18:56:10]

I don't know. My concern when I did this originally was that we'd lose the
invalidation as it won't get added to the aggregator_.InvalidateRect() below. Is
that going to leave us failing to paint something we should have painted?

As I said, I don't understand this code well enough to know which is the right
direction to go .....

+  // PDF can trigger at any point. So, while we're attempting to paint it's
+  // possible for the JS to trigger and cause an invalidation.
   if (graphics_.is_null() && !has_pending_resize_)
     return;
 
@@ -151,7 +152,8 @@ void PaintManager::InvalidateRect(const pp::Rect& rect) {
   if (clipped_rect.IsEmpty())
     return;  // Nothing to do.
 
-  EnsureCallbackPending();
+  if (!in_paint_)
+    EnsureCallbackPending();
   aggregator_.InvalidateRect(clipped_rect);
 }