Add sfntly library for font subsetting used in print preview.

third_party/sfntly/src/subsetter/font_subsetter.h

Index: third_party/sfntly/src/subsetter/font_subsetter.h
diff --git a/third_party/sfntly/src/subsetter/font_subsetter.h b/third_party/sfntly/src/subsetter/font_subsetter.h
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+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef THIRD_PARTY_SFNTLY_SRC_SUBSETTER_FONT_SUBSETTER_H_
+#define THIRD_PARTY_SFNTLY_SRC_SUBSETTER_FONT_SUBSETTER_H_
+
+#include <cstddef>
+
+class SfntlyWrapper {
+ public:
+
+  // Font subsetting API
+  //
+  // Input TTF/TTC/OTF fonts, specify the glyph IDs to subset, and the subset
+  // font is returned in |output_buffer| (caller to delete[]).  Return value is
+  // the length of output_buffer allocated.
+  //
+  // If subsetting fails, a negative value is returned.  If none of the glyph
+  // IDs specified is found, the function will return 0.
+  //
+  // |font_name|      Font name, required for TTC files.  If specified NULL,
+  //                  the first available font is selected.
+  // |original_font|  Original font file contents.
+  // |font_size|      Size of |original_font| in bytes.
+  // |glyph_ids|      Glyph IDs to subset.  If the specified glyph ID is not
+  //                  found in the font file, it will be ignored silently.
+  // |glyph_count|    Number of glyph IDs in |glyph_ids|
+  // |output_buffer|  Generated subset font.  Caller to delete[].
+  static int SubsetFont(const char* font_name,
+                        const unsigned char* original_font,
+                        size_t font_size,
+                        const unsigned int* glyph_ids,
+                        size_t glyph_count,
+                        unsigned char** output_buffer);
+};
+
+#endif  // THIRD_PARTY_SFNTLY_SRC_SUBSETTER_FONT_SUBSETTER_H_