[pdf] Allow invalidation during paint.

pdf/paint_manager.cc

 // Copyright (c) 2010 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 "pdf/paint_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 123 matching lines @@
 
 void PaintManager::Invalidate() {
   if (graphics_.is_null() && !has_pending_resize_)
     return;
 
   EnsureCallbackPending();
   aggregator_.InvalidateRect(pp::Rect(GetEffectiveSize()));
 }
 
 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;
 
   // Clip the rect to the device area.
   pp::Rect clipped_rect = rect.Intersect(pp::Rect(GetEffectiveSize()));
   if (clipped_rect.IsEmpty())
     return;  // Nothing to do.
 
-  EnsureCallbackPending();
+  if (!in_paint_)
+    EnsureCallbackPending();
   aggregator_.InvalidateRect(clipped_rect);
 }
 
 void PaintManager::ScrollRect(const pp::Rect& clip_rect,
                               const pp::Point& amount) {
   DCHECK(!in_paint_);
 
   if (graphics_.is_null() && !has_pending_resize_)
     return;
 
@@ skipping 174 matching lines @@
   DCHECK(manual_callback_pending_);
   manual_callback_pending_ = false;
 
   // Just because we have a manual callback doesn't mean there are actually any
   // invalid regions. Even though we only schedule this callback when something
   // is pending, a Flush callback could have come in before this callback was
   // executed and that could have cleared the queue.
   if (aggregator_.HasPendingUpdate())
     DoPaint();
 }