Remove include/xml from public API.

Move SkDOM and ilk from include/xml to src/xml.

I have looked for uses of SkDOM in the depot using cs/ and have found none,
but this is not perfect. So, if this breaks external builds, revert it.

TBR=reed@google.com

Change-Id: I162a1977f0649b049c0f93f016701784d025996d
Reviewed-on: https://skia-review.googlesource.com/8447
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Herb Derby <herb@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index ffc5713..b1bfb01 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -67,7 +67,6 @@
   "include/svg",
   "include/utils",
   "include/utils/mac",
-  "include/xml",
 ]
 
 # Skia public API, generally provided by :skia.
@@ -112,6 +111,7 @@
     "src/sksl",
     "src/utils",
     "src/utils/win",
+    "src/xml",
     "third_party/etc1",
     "third_party/gif",
     "third_party/ktx",
diff --git a/include/xml/SkDOM.h b/src/xml/SkDOM.h
similarity index 98%
rename from include/xml/SkDOM.h
rename to src/xml/SkDOM.h
index aa7ea78..0ffb042 100644
--- a/include/xml/SkDOM.h
+++ b/src/xml/SkDOM.h
@@ -20,7 +20,7 @@
 class SkStream;
 class SkXMLParser;
 
-class SK_API SkDOM : public SkNoncopyable {
+class SkDOM : public SkNoncopyable {
 public:
     SkDOM();
     ~SkDOM();
diff --git a/include/xml/SkXMLParser.h b/src/xml/SkXMLParser.h
similarity index 100%
rename from include/xml/SkXMLParser.h
rename to src/xml/SkXMLParser.h
diff --git a/include/xml/SkXMLWriter.h b/src/xml/SkXMLWriter.h
similarity index 100%
rename from include/xml/SkXMLWriter.h
rename to src/xml/SkXMLWriter.h