Test virtual interface [NOT FOR REVIEW]

components/tracing/test/tracing_interface_simulator.h

Index: components/tracing/test/tracing_interface_simulator.h
diff --git a/components/tracing/test/tracing_interface_simulator.h b/components/tracing/test/tracing_interface_simulator.h
new file mode 100644
index 0000000000000000000000000000000000000000..4fdb56b261fb8e2751c543fed3bf85a0c4a2d856
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+++ b/components/tracing/test/tracing_interface_simulator.h
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+// Copyright 2017 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.
+
+#ifndef COMPONENTS_TRACING_TEST_TRACING_INTERFACE_SIMULATOR_H_
+#define COMPONENTS_TRACING_TEST_TRACING_INTERFACE_SIMULATOR_H_
+
+#include "base/trace_event/trace_event.h"
+
+namespace tracing {
+
+class TracingInterface {
+ public:
+  virtual base::trace_event::TraceEventHandle AddEvent(
+      const char *category, const unsigned char* cat_enabled,
+      char type, const char *name, bool copy_name) const = 0;
+  virtual const unsigned char*
+      GetCategoryPointer(const char *category) const = 0;
+};
+
+void InitTracingInterface();
+const TracingInterface* GetTracingInterface();
+
+base::trace_event::TraceEventHandle AddEventDirect(
+    const char *category, const unsigned char* cat_enabled,
+    char type, const char *name, bool copy_name);
+const unsigned char* GetCategoryPointerDirect(const char *category);
+
+
+#define TRACE_EVENT_VIRTUAL_TEST(category, name) \
+  TRACE_EVENT_VIRTUAL_TEST_BODY(category, name, \
+      cat_enabled_ptr_ ## __LINE__, cat_enabled_atomic_ ## __LINE__)
+
+#define TRACE_EVENT_VIRTUAL_TEST_BODY(category, name, enabled_ptr, enabled_atomic) \
+  static base::subtle::AtomicWord enabled_atomic = 0; \
+  const unsigned char* enabled_ptr = reinterpret_cast<const unsigned char*>( \
+      base::subtle::NoBarrier_Load(&enabled_atomic)); \
+  if (UNLIKELY(!enabled_ptr)) { \
+    enabled_ptr = GetTracingInterface()->GetCategoryPointer(category); \
+    base::subtle::NoBarrier_Store(&enabled_atomic, \
+        reinterpret_cast<base::subtle::AtomicWord>(enabled_ptr)); \
+  } \
+  trace_event_internal::ScopedTracer scoped_tracer_ ## __LINE__; \
+  if (UNLIKELY(*enabled_ptr)) { \
+    scoped_tracer_ ## __LINE__.Initialize(enabled_ptr, name, \
+        GetTracingInterface()->AddEvent(category, enabled_ptr, 'X', name, false)); \
+  }
+
+
+#define TRACE_EVENT_DIRECT_TEST(category, name) \
+  TRACE_EVENT_DIRECT_TEST_BODY(category, name, \
+      cat_enabled_ptr_ ## __LINE__, cat_enabled_atomic_ ## __LINE__)
+
+#define TRACE_EVENT_DIRECT_TEST_BODY(category, name, enabled_ptr, enabled_atomic) \
+  static base::subtle::AtomicWord enabled_atomic = 0; \
+  const unsigned char* enabled_ptr = reinterpret_cast<const unsigned char*>( \
+      base::subtle::NoBarrier_Load(&enabled_atomic)); \
+  if (UNLIKELY(!enabled_ptr)) { \
+    enabled_ptr = GetCategoryPointerDirect(category); \
+    base::subtle::NoBarrier_Store(&enabled_atomic, \
+        reinterpret_cast<base::subtle::AtomicWord>(enabled_ptr)); \
+  } \
+  trace_event_internal::ScopedTracer scoped_tracer_ ## __LINE__; \
+  if (UNLIKELY(*enabled_ptr)) { \
+    scoped_tracer_ ## __LINE__.Initialize(enabled_ptr, name, \
+        AddEventDirect(category, enabled_ptr, 'X', name, false)); \
+  }
+
+}  // namespace tracing
+
+#endif  // COMPONENTS_TRACING_TEST_TRACING_INTERFACE_SIMULATOR_H_