Add a templated priority queue class.

Review URL: https://codereview.chromium.org/914003004
diff --git a/gyp/core.gypi b/gyp/core.gypi
index 0e2f24f..6080148 100644
--- a/gyp/core.gypi
+++ b/gyp/core.gypi
@@ -203,6 +203,7 @@
         '<(skia_src_path)/core/SkTextBlob.cpp',
         '<(skia_src_path)/core/SkTextFormatParams.h',
         '<(skia_src_path)/core/SkTextMapStateProc.h',
+        '<(skia_src_path)/core/SkTDPQueue.h',
         '<(skia_src_path)/core/SkTHashCache.h',
         '<(skia_src_path)/core/SkTLList.h',
         '<(skia_src_path)/core/SkTLS.cpp',