Idle cleanup for worker context

cc/output/context_provider.cc

Index: cc/output/context_provider.cc
diff --git a/cc/output/context_provider.cc b/cc/output/context_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7842136c8f719e0ca05dc665202e991ffebcb017
--- /dev/null
+++ b/cc/output/context_provider.cc
@@ -0,0 +1,26 @@
+// Copyright (c) 2016 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 "cc/output/context_provider.h"
+
+namespace cc {
+
+ContextProvider::ScopedContextLock::ScopedContextLock(
+    ContextProvider* context_provider)
+    : context_provider_(context_provider),
+      context_lock_(*context_provider_->GetLock()) {
+  // Allow current thread to use |context_provider_|.
+  context_provider_->DetachFromThread();
+  busy_ = context_provider_->CacheController()->ClientBecameBusy();
+}
+
+ContextProvider::ScopedContextLock::~ScopedContextLock() {
+  // Let ContextCacheController know we are no longer busy.
+  context_provider_->CacheController()->ClientBecameNotBusy(std::move(busy_));
+
+  // Allow usage by thread for which |context_provider_| is bound to.
+  context_provider_->DetachFromThread();
+}
+
+}  // namespace cc