Reland: Add MemoryCoordinatorClient

third_party/WebKit/Source/platform/MemoryCoordinator.cpp

Index: third_party/WebKit/Source/platform/MemoryCoordinator.cpp
diff --git a/third_party/WebKit/Source/platform/MemoryCoordinator.cpp b/third_party/WebKit/Source/platform/MemoryCoordinator.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3a8f022b4023e78082f0f02fa82ea26b51cd5471
--- /dev/null
+++ b/third_party/WebKit/Source/platform/MemoryCoordinator.cpp
@@ -0,0 +1,66 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/MemoryCoordinator.h"
+
+#include "platform/TraceEvent.h"
+#include "platform/fonts/FontCache.h"
+#include "platform/graphics/ImageDecodingStore.h"
+#include "wtf/allocator/Partitions.h"
+
+namespace blink {
+
+MemoryCoordinator& MemoryCoordinator::instance()
+{
+    DEFINE_STATIC_LOCAL(Persistent<MemoryCoordinator>, external, (new MemoryCoordinator));
+    DCHECK(isMainThread());
+    return *external.get();
+}
+
+MemoryCoordinator::MemoryCoordinator()
+{
+}
+
+void MemoryCoordinator::registerClient(MemoryCoordinatorClient* client)
+{
+    DCHECK(isMainThread());
+    DCHECK(client);
+    DCHECK(!m_clients.contains(client));
+    m_clients.add(client);
+}
+
+void MemoryCoordinator::unregisterClient(MemoryCoordinatorClient* client)
+{
+    DCHECK(isMainThread());
+    m_clients.remove(client);
+}
+
+void MemoryCoordinator::purgeMemory()
+{
+    for (auto& client : m_clients)
+        client->purgeMemory();
+    WTF::Partitions::decommitFreeableMemory();
+}
+
+void MemoryCoordinator::onMemoryPressure(WebMemoryPressureLevel level)
+{
+    TRACE_EVENT0("blink", "MemoryCoordinator::onMemoryPressure");
+    for (auto& client : m_clients)
+        client->onMemoryPressure(level);
+    if (level == WebMemoryPressureLevelCritical) {
+        // Clear the image cache.
+        // TODO(tasak|bashi): Make ImageDecodingStore and FontCache be
+        // MemoryCoordinatorClients rather than clearing caches here.
+        ImageDecodingStore::instance().clear();
+        FontCache::fontCache()->invalidate();
+    }
+    WTF::Partitions::decommitFreeableMemory();
+}
+
+DEFINE_TRACE(MemoryCoordinator)
+{
+    visitor->trace(m_clients);
+}
+
+} // namespace blink