fontCache()->invalidate()

ここ、しかないな。

"fontcache - invalidate" 

     52 // static
     53 void WebFontCache::clear()
     54 {
     55     fontCache()->invalidate();
     56 }

    529 void FontCache::invalidate()
    530 {
    531     if (!gClients) {
    532         ASSERT(!gFontPlatformDataCache);
    533         return;
    534     }
    535 
    536     if (gFontPlatformDataCache) {
    537         deleteAllValues(*gFontPlatformDataCache);
    538         delete gFontPlatformDataCache;
    539         gFontPlatformDataCache = new FontPlatformDataCache;
    540     }
    541 
    542     gGeneration++;
    543 
    544     Vector<RefPtr<FontSelector> > clients;
    545     size_t numClients = gClients->size();
    546     clients.reserveInitialCapacity(numClients);
    547     HashSet<FontSelector*>::iterator end = gClients->end();
    548     for (HashSet<FontSelector*>::iterator it = gClients->begin(); it != end; ++it)
    549         clients.append(*it);
    550 
    551     ASSERT(numClients == clients.size());
    552     for (size_t i = 0; i < numClients; ++i)
    553         clients[i]->fontCacheInvalidated();
    554 
    555     purgeInactiveFontData();
    556 }