Bug 1514803 - Expose nsPNGEncoder header r=aosmond

Differential Revision: https://phabricator.services.mozilla.com/D14814

--HG--
extra : moz-landing-system : lando

image/encoders/png/nsPNGEncoder.h

@@ -3,7 +3,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef nsPNGEncoder_h
+#ifndef mozilla_image_encoders_png_nsPNGEncoder_h
+#define mozilla_image_encoders_png_nsPNGEncoder_h
 
 #include <png.h>
 
@@ -74,4 +75,4 @@ class nsPNGEncoder final : public imgIEncoder {
   // AsyncWait.
   ReentrantMonitor mReentrantMonitor;
 };
-#endif  // nsPNGEncoder_h
+#endif  // mozilla_image_encoders_png_nsPNGEncoder_h

image/moz.build

@@ -55,6 +55,7 @@ EXPORTS += [
 
 EXPORTS.mozilla.image += [
     'encoders/jpeg/nsJPEGEncoder.h',
+    'encoders/png/nsPNGEncoder.h',
     'ImageMemoryReporter.h',
     'RecyclingSourceSurface.h',
 ]