Update PDF backend to support fallback fonts on Android.

include/ports/SkTypeface_android.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkTypeface_android_DEFINED
 #define SkTypeface_android_DEFINED
@@ skipping 50 matching lines @@
  *  The original fontID is also provided. This is the initial font that was
  *  stored in the typeface of the caller. It is provided as an aid to choose
  *  the best next logical font. e.g. If the original font was bold or serif,
  *  but the 2nd in the logical chain was plain, then a subsequent call to
  *  get the 3rd can still inspect the original, and try to match its
  *  stylistic attributes.
  */
 SkTypeface* SkAndroidNextLogicalTypeface(SkFontID currFontID, SkFontID origFontID,
                                          const SkPaintOptionsAndroid& options);
 
+/**
+ * Given a glyphID (built using fallback font chaining) and its origin typeface
+ * return the actual typeface within the fallback chain that this glyphID
+ * resolves to. If no suitable typeface is found then NULL is returned. However,
+ * if returned typeface is not NULL it is assumed to be globally cached so the
+ * caller need not ref it.
+ *
+ * Optionally, if lower/upper bound params are provided and the returned
+ * typeface is not NULL, then these params are populated with the range of
+ * glyphIDs that this typeface is capable of resolving. The lower bound is
+ * inclusive while the upper bound is exclusive.
+ */
+SkTypeface* SkGetTypefaceForGlyphID(uint16_t glyphID, const SkTypeface* origTypeface,
+                                    const SkPaintOptionsAndroid& options,
+                                    int* lowerBounds = NULL, int* upperBounds = NULL);
+
 #endif // #ifdef SK_BUILD_FOR_ANDROID
 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
 
 #include "SkPaintOptionsAndroid.h"
 #include "../harfbuzz/src/harfbuzz-shaper.h"
 #include "../harfbuzz_ng/src/hb.h"
 
 /**
  *  Return a new typeface for a fallback script. If the script is
  *  not valid, or can not map to a font, returns null.
  *  @param  script   The harfbuzz script id.
  *  @param  style    The font style, for example bold
  *  @param  elegant  true if we want the web friendly elegant version of the font
  *  @return          reference to the matching typeface. Caller must call
  *                   unref() when they are done.
  */
 SK_API SkTypeface* SkCreateTypefaceForScriptNG(hb_script_t script, SkTypeface::Style style,
         SkPaintOptionsAndroid::FontVariant fontVariant = SkPaintOptionsAndroid::kDefault_Variant);
 
 SK_API SkTypeface* SkCreateTypefaceForScript(HB_Script script, SkTypeface::Style style,
         SkPaintOptionsAndroid::FontVariant fontVariant = SkPaintOptionsAndroid::kDefault_Variant);
 
 #endif // #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
 #endif // #ifndef SkTypeface_android_DEFINED