Defer deletion in PrintWebViewHelper while handling IPC messages.

components/printing/renderer/print_web_view_helper.h

 // Copyright (c) 2012 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.
 
 #ifndef COMPONENTS_PRINTING_RENDERER_PRINT_WEB_VIEW_HELPER_H_
 #define COMPONENTS_PRINTING_RENDERER_PRINT_WEB_VIEW_HELPER_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 431 matching lines @@
 
     // Cleanup after print preview finishes.
     void Finished();
 
     // Cleanup after print preview fails.
     void Failed(bool report_error);
 
     // Helper functions
     int GetNextPageNumber();
     bool IsRendering() const;
-    bool IsModifiable();
+    bool IsModifiable() const;
     bool HasSelection();
     bool IsLastPageOfPrintReadyMetafile() const;
     bool IsFinalPageRendered() const;
 
     // Setters
     void set_generate_draft_pages(bool generate_draft_pages);
     void set_error(enum PrintPreviewErrorBuckets error);
 
     // Getters
     // Original frame for which preview was requested.
@@ skipping 17 matching lines @@
     enum State {
       UNINITIALIZED,  // Not ready to render.
       INITIALIZED,    // Ready to render.
       RENDERING,      // Rendering.
       DONE            // Finished rendering.
     };
 
     // Reset some of the internal rendering context.
     void ClearContext();
 
+    void CalculateIsModifiable();
+
     // Specifies what to render for print preview.
     FrameReference source_frame_;
     blink::WebNode source_node_;
 
     std::unique_ptr<PrepareFrameAndViewForPrint> prep_frame_view_;
     std::unique_ptr<PdfMetafileSkia> metafile_;
 
     // Total page count in the renderer.
     int total_page_count_;
 
     // The current page to render.
     int current_page_index_;
 
     // List of page indices that need to be rendered.
     std::vector<int> pages_to_render_;
 
     // True, when draft pages needs to be generated.
     bool generate_draft_pages_;
 
+    // True, if the document source is modifiable. e.g. HTML and not PDF.
+    bool is_modifiable_;

[lfg, 2017/04/27 19:44:14]

This seems to be uninitialized in the constructor.

[Lei Zhang, 2017/04/27 20:31:24]

Right. It's not ever used until after one of the Init* methods get called. I'll
initialize since it's generally a good thing to do. I also added a DCHECK to
make sure we are not trying to access it when |state_| is UNINITIALIZED.

+
     // Specifies the total number of pages in the print ready metafile.
     int print_ready_metafile_page_count_;
 
     base::TimeDelta document_render_time_;
     base::TimeTicks begin_time_;
 
     enum PrintPreviewErrorBuckets error_;
 
     State state_;
+
+    DISALLOW_COPY_AND_ASSIGN(PrintPreviewContext);
   };
 
   class ScriptingThrottler {
    public:
     ScriptingThrottler();
 
     // Returns false if script initiated printing occurs too often.
     bool IsAllowed(blink::WebLocalFrame* frame);
 
     // Reset the counter for script initiated printing.
     // Scripted printing will be allowed to continue.
     void Reset();
 
    private:
     base::Time last_print_;
     int count_ = 0;
     DISALLOW_COPY_AND_ASSIGN(ScriptingThrottler);
   };
 
   ScriptingThrottler scripting_throttler_;
 
   bool print_node_in_progress_;
   PrintPreviewContext print_preview_context_;
   bool is_loading_;
   bool is_scripted_preview_delayed_;
   int ipc_nesting_level_;
+  bool render_frame_gone_;
 
   // Used to fix a race condition where the source is a PDF and print preview
   // hangs because RequestPrintPreview is called before DidStopLoading() is
   // called. This is a store for the RequestPrintPreview() call and its
   // parameters so that it can be invoked after DidStopLoading.
   base::Closure on_stop_loading_closure_;
 
   base::WeakPtrFactory<PrintWebViewHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintWebViewHelper);
 };
 
 }  // namespace printing
 
 #endif  // COMPONENTS_PRINTING_RENDERER_PRINT_WEB_VIEW_HELPER_H_