Assert complex precondition in SkGlyphCache::Visit.

src/core/SkGlyphCache.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 "SkGlyphCache.h"
 #include "SkGlyphCache_Globals.h"
 #include "SkGraphics.h"
@@ skipping 502 matching lines @@
 SkGlyphCache* SkGlyphCache::VisitCache(SkTypeface* typeface,
                                        const SkScalerContextEffects& effects,
                                        const SkDescriptor* desc,
                                        bool (*proc)(const SkGlyphCache*, void*),
                                        void* context) {
     if (!typeface) {
         typeface = SkTypeface::GetDefaultTypeface();
     }
     SkASSERT(desc);
 
+    // Precondition: the typeface id must be the fFontID in the descriptor
+    SkDEBUGCODE(
+        uint32_t length;
+        const SkScalerContext::Rec* rec = static_cast<const SkScalerContext::Rec*>(
+            desc->findEntry(kRec_SkDescriptorTag, &length));
+        SkASSERT(rec);
+        SkASSERT(length == sizeof(*rec));
+        SkASSERT(typeface->uniqueID() == rec->fFontID);
+    )
+
     SkGlyphCache_Globals& globals = get_globals();
     SkGlyphCache*         cache;
 
     {
         Exclusive ac(globals.fLock);
 
         globals.validate();
 
         for (cache = globals.internalGetHead(); cache != nullptr; cache = cache->fNext) {
             if (*cache->fDesc == *desc) {
@@ skipping 284 matching lines @@
 }
 
 void SkGraphics::PurgeFontCache() {
     get_globals().purgeAll();
     SkTypefaceCache::PurgeAll();
 }
 
 // TODO(herb): clean up TLS apis.
 size_t SkGraphics::GetTLSFontCacheLimit() { return 0; }
 void SkGraphics::SetTLSFontCacheLimit(size_t bytes) { }