Take mutex when calling into FreeType.

src/ports/SkFontHost_FreeType.cpp

Index: src/ports/SkFontHost_FreeType.cpp
diff --git a/src/ports/SkFontHost_FreeType.cpp b/src/ports/SkFontHost_FreeType.cpp
index 32eafad87c903098a02f179ee7f200428fd2d018..e8b72b5e090f3e3560ba6b6231bff34d55f87667 100644
--- a/src/ports/SkFontHost_FreeType.cpp
+++ b/src/ports/SkFontHost_FreeType.cpp
@@ -949,6 +949,7 @@ SkScalerContext_FreeType::~SkScalerContext_FreeType() {
     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",
@@ -968,10 +969,12 @@ unsigned SkScalerContext_FreeType::generateGlyphCount() {
 }
 
 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 );