Clear the PrintContext in WebLocalFrameImpl::Close().

third_party/WebKit/Source/core/page/PrintContext.h

 /*
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2007 Apple Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 13 matching lines @@
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 #include "platform/wtf/Forward.h"
 #include "platform/wtf/HashMap.h"
 #include "platform/wtf/Vector.h"
 #include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
 class Element;
-class LocalFrame;
 class FloatRect;
 class FloatSize;
 class GraphicsContext;
 class IntRect;
+class LocalFrame;
 class Node;
 
 class CORE_EXPORT PrintContext
     : public GarbageCollectedFinalized<PrintContext> {
  public:
   explicit PrintContext(LocalFrame*);
   virtual ~PrintContext();
 
   LocalFrame* GetFrame() const { return frame_; }
 
   // Break up a page into rects without relayout.
   // FIXME: This means that CSS page breaks won't be on page boundary if the
   // size is different than what was passed to BeginPrintMode(). That's probably
   // not always desirable.
   // FIXME: Header and footer height should be applied before layout, not after.
   // FIXME: The printRect argument is only used to determine page aspect ratio,
   // it would be better to pass a FloatSize with page dimensions instead.
   virtual void ComputePageRects(const FloatRect& print_rect,
                                 float header_height,
                                 float footer_height,
                                 float user_scale_factor,
                                 float& out_page_height);
 
   // Deprecated. Page size computation is already in this class, clients
   // shouldn't be copying it.
-  // FIXME: Everyone passes |false| for the second paramer. We should remove the
-  // second parameter.
   virtual void ComputePageRectsWithPageSize(
       const FloatSize& page_size_in_pixels);
 
   // These are only valid after page rects are computed.
   size_t PageCount() const { return page_rects_.size(); }
   const IntRect& PageRect(size_t page_number) const {
     return page_rects_[page_number];
   }
   const Vector<IntRect>& PageRects() const { return page_rects_; }
 
@@ skipping 19 matching lines @@
                                            int height,
                                            int margin_top,
                                            int margin_right,
                                            int margin_bottom,
                                            int margin_left);
   static int NumberOfPages(LocalFrame*, const FloatSize& page_size_in_pixels);
 
   DECLARE_VIRTUAL_TRACE();
 
  protected:
+  friend class PrintContextTest;
+
   void OutputLinkedDestinations(GraphicsContext&, const IntRect& page_rect);
 
   Member<LocalFrame> frame_;
   Vector<IntRect> page_rects_;
 
  private:
   void ComputePageRectsWithPageSizeInternal(
       const FloatSize& page_size_in_pixels);
   void CollectLinkedDestinations(Node*);
+  bool IsFrameValid() const;
 
   // Used to prevent misuses of BeginPrintMode() and EndPrintMode() (e.g., call
   // EndPrintMode without BeginPrintMode).
   bool is_printing_;
 
   HeapHashMap<String, Member<Element>> linked_destinations_;
   bool linked_destinations_valid_;
 };
 
+class ScopedPrintContext {
+  STACK_ALLOCATED();
+
+ public:
+  explicit ScopedPrintContext(LocalFrame*);
+  ~ScopedPrintContext();
+
+  PrintContext* operator->() const { return context_.Get(); }
+
+ private:
+  Member<PrintContext> context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedPrintContext);
+};
+
 }  // namespace blink
 
 #endif