store MetafileSkiaWrapper in plugin instead of canvas

content/renderer/pepper/pepper_plugin_instance_impl.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 CONTENT_RENDERER_PEPPER_PEPPER_PLUGIN_INSTANCE_IMPL_H_
 #define CONTENT_RENDERER_PEPPER_PEPPER_PLUGIN_INSTANCE_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 80 matching lines @@
 class Rect;
 }
 
 namespace ppapi {
 class Resource;
 struct InputEventData;
 struct PPP_Instance_Combined;
 class ScopedPPVar;
 }
 
+namespace printing {
+class MetafileSkiaWrapper;
+}
+
 namespace content {
 
 class ContentDecryptorDelegate;
 class FullscreenContainer;
 class MessageChannel;
 class PepperAudioController;
 class PepperCompositorHost;
 class PepperGraphics2DHost;
 class PluginInstanceThrottlerImpl;
 class PluginModule;
@@ skipping 527 matching lines @@
   void SendDidChangeView();
 
   // Reports the current plugin geometry to the plugin by calling
   // DidChangeView.
   void ReportGeometry();
 
   // Queries the plugin for supported print formats and sets |format| to the
   // best format to use. Returns false if the plugin does not support any
   // print format that we can handle (we can handle only PDF).
   bool GetPreferredPrintOutputFormat(PP_PrintOutputFormat_Dev* format);
-  bool PrintPDFOutput(PP_Resource print_output, blink::WebCanvas* canvas);
+  bool PrintPDFOutput(PP_Resource print_output,
+                      printing::MetafileSkiaWrapper* wrapper);
 
   // Updates the layer for compositing. This creates a layer and attaches to the
   // container if:
   // - we have a bound Graphics3D and the Graphics3D has a texture, OR
   //   we have a bound Graphics2D and are using software compositing
   // - we are not in Flash full-screen mode (or transitioning to it)
   // Otherwise it destroys the layer.
   // It does either operation lazily.
   // force_creation: Force UpdateLayer() to recreate the layer and attaches
   //   to the container. Set to true if the bound device has been changed.
   void UpdateLayer(bool force_creation);
 
   // Internal helper function for PrintPage().
   void PrintPageHelper(PP_PrintPageNumberRange_Dev* page_ranges,
-                       int num_ranges,
-                       blink::WebCanvas* canvas);
+                       int num_ranges, printing::MetafileSkiaWrapper* wrapper);
 
   void DoSetCursor(blink::WebCursorInfo* cursor);
 
   // Internal helper functions for HandleCompositionXXX().
   bool SendCompositionEventToPlugin(PP_InputEvent_Type type,
                                     const base::string16& text);
   bool SendCompositionEventWithUnderlineInformationToPlugin(
       PP_InputEvent_Type type,
       const base::string16& text,
       const std::vector<blink::WebCompositionUnderline>& underlines,
@@ skipping 153 matching lines @@
 #if defined(OS_MACOSX)
   // On the Mac, when we draw the bitmap to the PDFContext, it seems necessary
   // to keep the pixels valid until CGContextEndPage is called. We use this
   // variable to hold on to the pixels.
   scoped_refptr<PPB_ImageData_Impl> last_printed_page_;
 #endif  // defined(OS_MACOSX)
   // Always when printing to PDF on Linux and when printing for preview on Mac
   // and Win, the entire document goes into one metafile.  However, when users
   // print only a subset of all the pages, it is impossible to know if a call
   // to PrintPage() is the last call. Thus in PrintPage(), just store the page
-  // number in |ranges_|. The hack is in PrintEnd(), where a valid |canvas_|
+  // number in |ranges_|. The hack is in PrintEnd(), where a valid
+  // |metafile_wrapper_|

[bbudge, 2016/11/17 22:37:00]

nit: formatting is a little hard to read here.

   // is preserved in PrintWebViewHelper::PrintPages. This makes it possible
   // to generate the entire PDF given the variables below:
   //
-  // The most recently used WebCanvas to be used in printEnd(). Caller must
-  // ensure that it remains valid until that point.
-  blink::WebCanvas* canvas_;
+  // The most recently used metafile wrapper from the most recently used canvas
+  sk_sp<printing::MetafileSkiaWrapper> metafile_wrapper_;

[Lei Zhang, 2016/11/18 02:25:53]

So this is slightly problematic as-is because it always pulls in printing as a
dependency, and there are build configs where printing is turned off. I'll see
if we can ifdef this...

   // An array of page ranges.
   std::vector<PP_PrintPageNumberRange_Dev> ranges_;
 
   scoped_refptr<ppapi::Resource> gamepad_impl_;
   scoped_refptr<ppapi::Resource> uma_private_impl_;
 
   // The plugin print interface.
   const PPP_Printing_Dev* plugin_print_interface_;
 
   // The plugin 3D interface.
@@ skipping 130 matching lines @@
   // view change events.
   base::WeakPtrFactory<PepperPluginInstanceImpl> view_change_weak_ptr_factory_;
   base::WeakPtrFactory<PepperPluginInstanceImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PepperPluginInstanceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_PEPPER_PEPPER_PLUGIN_INSTANCE_IMPL_H_