Remove mutex for retrieving default typeface.

src/core/SkTypeface.cpp

Index: src/core/SkTypeface.cpp
diff --git a/src/core/SkTypeface.cpp b/src/core/SkTypeface.cpp
index 3c15878f737bc5c10a1d38b9d0377487300e8e38..ba9e765e99df11da1f869f54e9f2aee48ba113cc 100644
--- a/src/core/SkTypeface.cpp
+++ b/src/core/SkTypeface.cpp
@@ -78,19 +78,12 @@ protected:
 
 }
 
-SK_DECLARE_STATIC_MUTEX(gCreateDefaultMutex);
-
 SkTypeface* SkTypeface::GetDefaultTypeface(Style style) {
     static SkOnce once[4];
     static SkTypeface* defaults[4];
 
     SkASSERT((int)style < 4);
     once[style]([style] {
-        // It is not safe to call FontConfigTypeface::LegacyCreateTypeface concurrently.
-        // To be safe, we serialize here with a mutex so only one call to
-        // CreateTypeface is happening at any given time.
-        // TODO(bungeman, mtklein): This is sad.  Make our fontconfig code safe?
-        SkAutoMutexAcquire lock(&gCreateDefaultMutex);
         SkAutoTUnref<SkFontMgr> fm(SkFontMgr::RefDefault());
         SkTypeface* t = fm->legacyCreateTypeface(nullptr, SkFontStyle::FromOldStyle(style));
         defaults[style] = t ? t : SkEmptyTypeface::Create();