Improve LayoutMultiColumnFlowThread::IsPageLogicalHeightKnown().

third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.h

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 235 matching lines @@
   // layout (during column set layout), in which case we need another layout
   // pass. Column heights may change after flow thread layout because of
   // balancing. We may have to do multiple layout passes, depending on how the
   // contents is fitted to the changed column heights. In most cases, laying out
   // again twice or even just once will suffice. Sometimes we need more passes
   // than that, though, but the number of retries should not exceed the number
   // of columns, unless we have a bug.
   bool ColumnHeightsChanged() const { return column_heights_changed_; }
   void SetColumnHeightsChanged() { column_heights_changed_ = true; }
 
+  // Finish multicol layout. Returns true if we're really done, or false if we
+  // need another layout pass (typically because columns got new heights in the
+  // previous pass, so that we need to refragment).
+  bool FinishLayout();
+
   void ColumnRuleStyleDidChange();
 
   // Remove the spanner placeholder and return true if the specified object is
   // no longer a valid spanner.
   bool RemoveSpannerPlaceholderIfNoLongerValid(
       LayoutBox* spanner_object_in_flow_thread);
 
   LayoutMultiColumnFlowThread* EnclosingFlowThread(
       AncestorSearchConstraint = kIsolateUnbreakableContainers) const;
   FragmentationContext* EnclosingFragmentationContext(
@@ skipping 79 matching lines @@
   LayoutUnit column_height_available_;
 
   // Cached block offset from this flow thread to the enclosing fragmentation
   // context, if any. In
   // the coordinate space of the enclosing fragmentation context.
   LayoutUnit block_offset_in_enclosing_fragmentation_context_;
 
   // Set when column heights are out of sync with actual layout.
   bool column_heights_changed_;
 
+  bool all_columns_have_known_height_ = false;
+
   // Always true for regular multicol. False for paged-y overflow.
   bool progression_is_inline_;
 
   bool is_being_evacuated_;
 
   // Specifies whether the the descendant whose style is about to change could
   // contain spanners or not. The flag is set in
   // flowThreadDescendantStyleWillChange(), and then checked in
   // flowThreadDescendantStyleDidChange().
   static bool could_contain_spanners_;
 
   static bool toggle_spanners_if_needed_;
 };
 
 // Cannot use DEFINE_LAYOUT_OBJECT_TYPE_CASTS here, because
 // isMultiColumnFlowThread() is defined in LayoutFlowThread, not in
 // LayoutObject.
 DEFINE_TYPE_CASTS(LayoutMultiColumnFlowThread,
                   LayoutFlowThread,
                   object,
                   object->IsLayoutMultiColumnFlowThread(),
                   object.IsLayoutMultiColumnFlowThread());
 
 }  // namespace blink
 
 #endif  // LayoutMultiColumnFlowThread_h