SkPDF: Add SkPDFCanvas to intercept some draw calls

src/pdf/SkPDFDocument.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFCanon.h"
+#include "SkPDFCanvas.h"
 #include "SkPDFDevice.h"
 #include "SkPDFDocument.h"
 #include "SkPDFFont.h"
 #include "SkPDFMetadata.h"
 #include "SkPDFStream.h"
 #include "SkPDFTypes.h"
 #include "SkPDFUtils.h"
 #include "SkStream.h"
 
 static void emit_pdf_header(SkWStream* stream) {
@@ skipping 307 matching lines @@
 
 protected:
     SkCanvas* onBeginPage(SkScalar width, SkScalar height,
                           const SkRect& trimBox) override {
         SkASSERT(!fCanvas.get());
 
         SkISize pageSize = SkISize::Make(
                 SkScalarRoundToInt(width), SkScalarRoundToInt(height));
         sk_sp<SkPDFDevice> device(
                 SkPDFDevice::Create(pageSize, fRasterDpi, &fCanon));
-        fCanvas.reset(new SkCanvas(device.get()));
+        fCanvas = sk_make_sp<SkPDFCanvas>(device);
         fPageDevices.push_back(std::move(device));
         fCanvas->clipRect(trimBox);
         fCanvas->translate(trimBox.x(), trimBox.y());
         return fCanvas.get();
     }
 
     void onEndPage() override {
         SkASSERT(fCanvas.get());
         fCanvas->flush();
         fCanvas.reset(nullptr);
@@ skipping 49 matching lines @@
     return SkPDFMakeDocument(stream, nullptr, dpi, jpegEncoder).release();
 }
 
 SkDocument* SkDocument::CreatePDF(const char path[], SkScalar dpi) {
     auto delete_wstream = [](SkWStream* stream, bool) { delete stream; };
     SkAutoTDelete<SkFILEWStream> stream(new SkFILEWStream(path));
     return stream->isValid()
         ? SkPDFMakeDocument(stream.release(), delete_wstream, dpi, nullptr).release()
         : nullptr;
 }