Free worker context resources on idle.

cc/output/context_provider.cc

+// 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()),
+      busy_(context_provider_->ContextSupport()->ClientBecameBusy()) {
+  // Allow current thread to use |context_provider_|.
+  context_provider_->DetachFromThread();

[danakj, 2016/08/23 01:26:24]

You don't need to do this before ClientBecameBusy?

[ericrk, 2016/08/24 18:32:21]

The detach/attach is only necessary before access to the GL context itself. For
helper functions like the busy handler, this shouldn't matter (as long as we
have the lock acquired) -- but I'm happy to move it after if that would keep
things more understandable - WDYT?

+}
+
+ContextProvider::ScopedContextLock::~ScopedContextLock() {
+  // Let ContextSupport know we are no longer busy.
+  context_provider_->ContextSupport()->ClientBecameNotBusy(std::move(busy_));
+
+  // Allow usage by thread for which |context_provider_| is bound to.
+  context_provider_->DetachFromThread();
+}
+
+}  // namespace cc