Allow calling FontCache::purge() at any timing

third_party/WebKit/Source/platform/fonts/FontCache.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 376 matching lines @@
   DEFINE_STATIC_LOCAL(CustomCountHistogram, shapeCacheHistogram,
                       ("Blink.Fonts.ShapeCache", 1, 1000000, 50));
   shapeCacheHistogram.count(items);
 }
 
 void FontCache::invalidateShapeCache() {
   purgeFallbackListShaperCache();
 }
 
 void FontCache::purge(PurgeSeverity PurgeSeverity) {
-  // We should never be forcing the purge while the FontCachePurgePreventer is
-  // in scope.
-  ASSERT(!m_purgePreventCount || PurgeSeverity == PurgeIfNeeded);
+  // Ideally we should never be forcing the purge while the
+  // FontCachePurgePreventer is in scope, but we call purge() at any timing
+  // via MemoryCoordinator.
   if (m_purgePreventCount)
     return;
 
   if (!gFontDataCache || !gFontDataCache->purge(PurgeSeverity))
     return;
 
   purgePlatformFontDataCache();
   purgeFontVerticalDataCache();
   purgeFallbackListShaperCache();
 }
@@ skipping 75 matching lines @@
   for (iter = gFallbackListShaperCache->begin();
        iter != gFallbackListShaperCache->end(); ++iter) {
     shapeResultCacheSize += iter->value->byteSize();
   }
   dump->AddScalar("size", "bytes", shapeResultCacheSize);
   memoryDump->AddSuballocation(dump->guid(),
                                WTF::Partitions::kAllocatedObjectPoolName);
 }
 
 }  // namespace blink