cc: Drop ContextProvider references on the impl thread before quitting

cc/resources/texture_mailbox_deleter_unittest.cc

Index: cc/resources/texture_mailbox_deleter_unittest.cc
diff --git a/cc/resources/texture_mailbox_deleter_unittest.cc b/cc/resources/texture_mailbox_deleter_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e08984e7583268b3a48e64e0723e3c62af7f1c5f
--- /dev/null
+++ b/cc/resources/texture_mailbox_deleter_unittest.cc
@@ -0,0 +1,39 @@
+// Copyright 2013 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/resources/texture_mailbox_deleter.h"
+
+#include "cc/debug/test_context_provider.h"
+#include "cc/debug/test_web_graphics_context_3d.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+namespace {
+
+TEST(TextureMailboxDeleterTest, Destroy) {
+  scoped_ptr<TextureMailboxDeleter> deleter(new TextureMailboxDeleter);
+
+  scoped_refptr<TestContextProvider> context_provider =
+      TestContextProvider::Create();
+  context_provider->BindToCurrentThread();
+
+  unsigned texture_id = context_provider->Context3d()->createTexture();
+
+  EXPECT_TRUE(context_provider->HasOneRef());
+  EXPECT_EQ(1u, context_provider->TestContext3d()->NumTextures());
+
+  TextureMailbox::ReleaseCallback cb =
+      deleter->GetReleaseCallback(context_provider, texture_id);
+  EXPECT_FALSE(context_provider->HasOneRef());
+  EXPECT_EQ(1u, context_provider->TestContext3d()->NumTextures());
+
+  // When the deleter is destroyed, it immediately drops its ref on the
+  // ContextProvider, and deletes the texture.
+  deleter.reset();
+  EXPECT_TRUE(context_provider->HasOneRef());
+  EXPECT_EQ(0u, context_provider->TestContext3d()->NumTextures());
+}
+
+}  // namespace
+}  // namespace cc