store MetafileSkiaWrapper in plugin instead of canvas

content/renderer/pepper/pepper_plugin_instance_impl.cc

Index: content/renderer/pepper/pepper_plugin_instance_impl.cc
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.cc b/content/renderer/pepper/pepper_plugin_instance_impl.cc
index 367fa644a0a51ab6ae18f33ae221eaa7601ac5db..a7b5dca930b2f7dd63835f97833d74ce2e964735 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.cc
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.cc
@@ -94,6 +94,7 @@
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/ppb_buffer_api.h"
 #include "printing/features/features.h"
+#include "printing/metafile_skia_wrapper.h"

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

BTW, this is already on line 135.

 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/URLConversion.h"
 #include "third_party/WebKit/public/platform/WebCursorInfo.h"
@@ -1798,7 +1799,7 @@ int PepperPluginInstanceImpl::PrintBegin(const WebPrintParams& print_params) {
   if (!num_pages)
     return 0;
   current_print_settings_ = print_settings;
-  canvas_ = nullptr;
+  metafile_wrapper_.reset();

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

Would a DCHECK(!metafile_wrapper_) make sense here? I'm assuming it's bad to
hold on to a metafile for a long time.

   ranges_.clear();
   return num_pages;
 }
@@ -1810,16 +1811,18 @@ void PepperPluginInstanceImpl::PrintPage(int page_number,
   PP_PrintPageNumberRange_Dev page_range;
   page_range.first_page_number = page_range.last_page_number = page_number;
   // The canvas only has a metafile on it for print preview.
-  bool save_for_later =
-      (printing::MetafileSkiaWrapper::GetMetafileFromCanvas(*canvas) != NULL);
+  sk_sp<printing::MetafileSkiaWrapper> wrapper =
+      printing::MetafileSkiaWrapper::RefFromCanvas(*canvas);
+  bool save_for_later = wrapper && wrapper->getMetafile();
 #if defined(OS_MACOSX)
   save_for_later = save_for_later && skia::IsPreviewMetafile(*canvas);
 #endif  // defined(OS_MACOSX)
+
   if (save_for_later) {
     ranges_.push_back(page_range);
-    canvas_ = canvas;
+    metafile_wrapper_ = wrapper;
   } else {
-    PrintPageHelper(&page_range, 1, canvas);
+    PrintPageHelper(&page_range, 1, wrapper.get());
   }
 #endif
 }
@@ -1827,7 +1830,7 @@ void PepperPluginInstanceImpl::PrintPage(int page_number,
 void PepperPluginInstanceImpl::PrintPageHelper(
     PP_PrintPageNumberRange_Dev* page_ranges,
     int num_ranges,
-    blink::WebCanvas* canvas) {
+    printing::MetafileSkiaWrapper* wrapper) {
   // Keep a reference on the stack. See NOTE above.
   scoped_refptr<PepperPluginInstanceImpl> ref(this);
   DCHECK(plugin_print_interface_);
@@ -1839,7 +1842,7 @@ void PepperPluginInstanceImpl::PrintPageHelper(
     return;
 
   if (current_print_settings_.format == PP_PRINTOUTPUTFORMAT_PDF)
-    PrintPDFOutput(print_output, canvas);
+    PrintPDFOutput(print_output, wrapper);
 
   // Now we need to release the print output resource.
   PluginModule::GetCore()->ReleaseResource(print_output);
@@ -1849,8 +1852,9 @@ void PepperPluginInstanceImpl::PrintEnd() {
   // Keep a reference on the stack. See NOTE above.
   scoped_refptr<PepperPluginInstanceImpl> ref(this);
   if (!ranges_.empty())

[Lei Zhang, 2016/11/18 01:53:37]

nit: needs curly braces now.

-    PrintPageHelper(&(ranges_.front()), ranges_.size(), canvas_);
-  canvas_ = nullptr;
+    PrintPageHelper(&(ranges_.front()), ranges_.size(),
+                    metafile_wrapper_.get());
+  metafile_wrapper_.reset();
   ranges_.clear();
 
   DCHECK(plugin_print_interface_);
@@ -2017,8 +2021,9 @@ bool PepperPluginInstanceImpl::IsViewAccelerated() {
   return view->isAcceleratedCompositingActive();
 }
 
-bool PepperPluginInstanceImpl::PrintPDFOutput(PP_Resource print_output,
-                                              blink::WebCanvas* canvas) {
+bool PepperPluginInstanceImpl::PrintPDFOutput(
+    PP_Resource print_output,
+    printing::MetafileSkiaWrapper* wrapper) {
 #if BUILDFLAG(ENABLE_PRINTING)
   ppapi::thunk::EnterResourceNoLock<PPB_Buffer_API> enter(print_output, true);
   if (enter.failed())
@@ -2031,7 +2036,7 @@ bool PepperPluginInstanceImpl::PrintPDFOutput(PP_Resource print_output,
   }
 
   printing::PdfMetafileSkia* metafile =
-      printing::MetafileSkiaWrapper::GetMetafileFromCanvas(*canvas);
+      wrapper ? wrapper->getMetafile() : nullptr;
   if (metafile)

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

How about:
if (wrapper) {
  printing::PdfMetafileSkia* metafile = ... etc.

     return metafile->InitFromData(mapper.data(), mapper.size());