SkPDF: move all pdf sources into src/pdf

src/doc/SkDocument_PDF_None.cpp

Index: src/doc/SkDocument_PDF_None.cpp
diff --git a/src/doc/SkDocument_PDF_None.cpp b/src/doc/SkDocument_PDF_None.cpp
deleted file mode 100644
index f146cba0186102701e4637316babddad72e1b592..0000000000000000000000000000000000000000
--- a/src/doc/SkDocument_PDF_None.cpp
+++ /dev/null
@@ -1,9 +0,0 @@
-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#include "SkDocument.h"
-SkDocument* SkDocument::CreatePDF(SkWStream*, SkScalar) { return  nullptr; }
-SkDocument* SkDocument::CreatePDF(const char path[], SkScalar) { return nullptr; }