Take mutex when calling into FreeType.

src/ports/SkFontHost_FreeType.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAdvancedTypefaceMetrics.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
@@ skipping 930 matching lines @@
     if (fFace != nullptr) {
         unref_ft_face(fFace);
     }
 
     unref_ft_library();
 }
 
 /*  We call this before each use of the fFace, since we may be sharing
     this face with other context (at different sizes).
 */
 FT_Error SkScalerContext_FreeType::setupSize() {

[herb_g, 2015/11/03 19:09:28]

Maybe change the name to indicate that this routine assumes a held lock.
setupSizeLocked?

+    gFTMutex.assertHeld();
     FT_Error err = FT_Activate_Size(fFTSize);
     if (err != 0) {
         SkDEBUGF(("SkScalerContext_FreeType::FT_Activate_Size(%s %s, 0x%x, 0x%x) returned 0x%x\n",
                   fFace->family_name, fFace->style_name, fScaleX, fScaleY, err));
         fFTSize = nullptr;
         return err;
     }
 
     // seems we need to reset this every time (not sure why, but without it
     // I get random italics from some other fFTSize)
     FT_Set_Transform(fFace, &fMatrix22, nullptr);
     return 0;
 }
 
 unsigned SkScalerContext_FreeType::generateGlyphCount() {
     return fFace->num_glyphs;
 }
 
 uint16_t SkScalerContext_FreeType::generateCharToGlyph(SkUnichar uni) {
+    SkAutoMutexAcquire  ac(gFTMutex);
     return SkToU16(FT_Get_Char_Index( fFace, uni ));
 }
 
 SkUnichar SkScalerContext_FreeType::generateGlyphToChar(uint16_t glyph) {
+    SkAutoMutexAcquire  ac(gFTMutex);
     // iterate through each cmap entry, looking for matching glyph indices
     FT_UInt glyphIndex;
     SkUnichar charCode = FT_Get_First_Char( fFace, &glyphIndex );
 
     while (glyphIndex != 0) {
         if (glyphIndex == glyph) {
             return charCode;
         }
         charCode = FT_Get_Next_Char( fFace, charCode, &glyphIndex );
     }
@@ skipping 746 matching lines @@
             (*axes)[i].fTag = ftAxis.tag;
             (*axes)[i].fMinimum = ftAxis.minimum;
             (*axes)[i].fDefault = ftAxis.def;
             (*axes)[i].fMaximum = ftAxis.maximum;
         }
     }
 
     FT_Done_Face(face);
     return true;
 }