Revert of Make fID and MixedID calculations private (patchset #5 id:80001 of https://codereview.chromium.org/939123002/)

Reason for revert:
This actually *does* change the public API - fID is now private, and it was being used on Android. See https://android-build.storage.googleapis.com/builds/git_master-skia-linux-volantis-userdebug/1751533/5242b865d3e9bebc650c9b326dfa9d68c8bd1f59562bf32b85301fb984dc8b26/logs/build.log?Signature=Q0el9M4kTu1KQ8u02KX9TH1Pa22y9BkDK1IW%2B9OeJJNfrDEVzLXAz0XQ%2BHHQM8xVjft06jZJva1V8InZmgjcOk6PdZQbQW6XwwsHLKsbpbAE48iTWH3AlJAAoTtj9cifzgeHW8g80IcVxwHXmINRER%2BLPz3eHGisgfTTFUoWYCc%3D&GoogleAccessId=701025073339-mqn0q2nvir9iurm6q5d00tdv7blbgvjr%40developer.gserviceaccount.com&Expires=1424786471 :

In file included from frameworks/base/libs/hwui/tests/../font/Font.cpp:26:0:
external/skia/src/core/SkGlyph.h: In member function 'android::uirenderer::CachedGlyphInfo* android::uirenderer::Font::cacheGlyph(const SkPaint*, glyph_t, bool)':
external/skia/src/core/SkGlyph.h:157:17: error: 'uint32_t SkGlyph::fID' is private
     uint32_t    fID;
                 ^
frameworks/base/libs/hwui/tests/../font/Font.cpp:482:39: error: within this context
     newGlyph->mGlyphIndex = skiaGlyph.fID;

We need to update Android in order to hide fID.

Original issue's description:
> BUG=skia:
>
> (mtklein from here on)
> No public API changes.
> TBR=reed@google.com
>
> Committed: https://skia.googlesource.com/skia/+/f8d24e2c0c7b44b7ccf20e40890514db4cde7b15

TBR=mtklein@google.com,herb@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/951353002
11 files changed