Update Context Client Visibility to use Scoped Pattern

cc/test/test_context_support.cc

Index: cc/test/test_context_support.cc
diff --git a/cc/test/test_context_support.cc b/cc/test/test_context_support.cc
index 7a47780e4d56369ffc6519477a2c33ff643616f3..d3ec892fc5b48ad7ffe76a5044064de916039031 100644
--- a/cc/test/test_context_support.cc
+++ b/cc/test/test_context_support.cc
@@ -9,13 +9,32 @@
 
 #include "base/bind.h"
 #include "base/location.h"
+#include "base/memory/ptr_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 
 namespace cc {
+namespace {
+
+// Class that DCHECKs if it is destructed without first having Release called.
+class ScopedVisibilityImpl : public gpu::ContextSupport::ScopedVisibility {
+ public:
+  explicit ScopedVisibilityImpl(gpu::ContextSupport* context_support)
+      : initial_context_support_(context_support) {}
+  ~ScopedVisibilityImpl() { DCHECK(!initial_context_support_); }
+
+  void Release(gpu::ContextSupport* context_support) {
+    DCHECK_EQ(initial_context_support_, context_support);
+    initial_context_support_ = nullptr;
+  }
+
+ private:
+  const gpu::ContextSupport* initial_context_support_;
+};
 
-TestContextSupport::TestContextSupport()
-    : out_of_order_callbacks_(false), weak_ptr_factory_(this) {}
+}  // namespace
+
+TestContextSupport::TestContextSupport() : weak_ptr_factory_(this) {}
 
 TestContextSupport::~TestContextSupport() {}
 
@@ -35,9 +54,7 @@ void TestContextSupport::SignalQuery(uint32_t query,
                             weak_ptr_factory_.GetWeakPtr()));
 }
 
-void TestContextSupport::SetAggressivelyFreeResources(
-    bool aggressively_free_resources) {
-}
+void TestContextSupport::TrimResources() {}
 
 void TestContextSupport::CallAllSyncPointCallbacks() {
   size_t size = sync_point_callbacks_.size();
@@ -91,18 +108,22 @@ uint64_t TestContextSupport::ShareGroupTracingGUID() const {
 void TestContextSupport::SetErrorMessageCallback(
     const base::Callback<void(const char*, int32_t)>& callback) {}
 
-void TestContextSupport::SetClientVisible(int client_id, bool is_visible) {
-  if (is_visible) {
-    visible_clients_.insert(client_id);
-  } else {
-    auto found = visible_clients_.find(client_id);
-    if (found != visible_clients_.end())
-      visible_clients_.erase(found);
-  }
+std::unique_ptr<gpu::ContextSupport::ScopedVisibility>
+TestContextSupport::ClientBecameVisible() {
+  ++num_visible_clients_;
+  return base::MakeUnique<ScopedVisibilityImpl>(this);
+}
+
+void TestContextSupport::ClientBecameNotVisible(
+    std::unique_ptr<ScopedVisibility> visibility) {
+  DCHECK(visibility);
+  DCHECK_GT(num_visible_clients_, 0u);
+  --num_visible_clients_;
+  static_cast<ScopedVisibilityImpl*>(visibility.get())->Release(this);
 }
 
 bool TestContextSupport::AnyClientsVisible() const {
-  return !visible_clients_.empty();
+  return num_visible_clients_ > 0;
 }
 
 }  // namespace cc