WebFontCache

この関数はAndroidでは使ってないようだ。
コンパイルで通らないっぽい。

    400 void ChromeRenderProcessObserver::OnPurgeMemory() {
    401   RenderThread::Get()->EnsureWebKitInitialized();
    402 
    403   // Clear the object cache (as much as possible; some live objects cannot be
    404   // freed).
    405   WebCache::clear();
    406 
    407   // Clear the font/glyph cache.
    408   WebFontCache::clear();            <==========
    409 
    410   // Clear the Cross-Origin Preflight cache.
    411   WebCrossOriginPreflightResultCache::clear();
    412 
    413   // Release all freeable memory from the SQLite process-global page cache (a
    414   // low-level object which backs the Connection-specific page caches).
    415   while (sqlite3_release_memory(std::numeric_limits<int>::max()) > 0) {
    416   }
    417 
    418   v8::V8::LowMemoryNotification();
    419 
    420   // Tell our allocator to release any free pages it's still holding.
    421   base::allocator::ReleaseFreeMemory();
    422 
    423   if (client_)
    424     client_->OnPurgeMemory();
    425 }