Reland: Add trace event Pepper API

ppapi/shared_impl/ppb_trace_event_impl.cc

+// Copyright (c) 2012 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 "ppapi/shared_impl/ppb_trace_event_impl.h"
+
+#include "base/debug/trace_event.h"
+#include "ppapi/thunk/thunk.h"
+
+
+namespace ppapi {
+
+// PPB_Trace_Event_Dev is a shared implementation because Trace Events can be
+// sent from either the plugin process or renderer process depending on whether
+// the plugin is in- or out-of-process.  Also, for NaCl plugins these functions
+// will be executed from untrusted code and handled appropriately by tracing
+// functionality in the IRT.
+
+// static
+void* TraceEventImpl::GetCategoryEnabled(const char* category_name) {
+  // This casting is here because all mem_t return types in Pepper are void* and
+  // non-const.  All mem_t parameters are const void* so there is no way to
+  // return a pointer type to the caller without some const_cast.  The pointer
+  // type the tracing system works with is normally unsigned char*.
+  return const_cast<void*>(static_cast<const void*>(
+      base::debug::TraceLog::GetInstance()->GetCategoryEnabled(category_name)));
+}
+
+// static
+void TraceEventImpl::AddTraceEvent(int8_t phase,
+                                      const void* category_enabled,
+                                      const char* name,
+                                      uint64_t id,
+                                      uint32_t num_args,
+                                      const char* arg_names[],
+                                      const uint8_t arg_types[],
+                                      const uint64_t arg_values[],
+                                      uint8_t flags) {
+  base::debug::TraceLog::GetInstance()->AddTraceEvent(phase,
+      static_cast<const unsigned char*>(category_enabled), name, id, num_args,
+      arg_names, arg_types,
+      // This cast is necessary for LP64 systems, where uint64_t is defined as
+      // an unsigned long int, but trace_event internals are hermetic and
+      // accepts an |unsigned long long*|.  The pointer types are compatible but
+      // the compiler throws an error without an explicit cast.
+      reinterpret_cast<const unsigned long long*>(arg_values), flags);
+}
+
+// static
+void TraceEventImpl::SetThreadName(const char* thread_name) {
+  base::PlatformThread::SetName(thread_name);
+}
+
+namespace {
+
+const PPB_Trace_Event_Dev g_ppb_trace_event_thunk = {
+  &TraceEventImpl::GetCategoryEnabled,
+  &TraceEventImpl::AddTraceEvent,
+  &TraceEventImpl::SetThreadName,
+};
+
+}  // namespace ppapi
+
+}  // namespace
+
+namespace ppapi {
+namespace thunk {
+
+const PPB_Trace_Event_Dev_0_1* GetPPB_Trace_Event_Dev_0_1_Thunk() {
+  return &g_ppb_trace_event_thunk;
+}
+
+}  // namespace thunk
+}  // namespace ppapi