Cleanup trace_event.h, fix webkit API naming.

base/debug/trace_event.h

 // 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.
 
 // This header is designed to give you trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // event to some other universe, you can copy-and-paste this file,
 // implement the TRACE_EVENT_API macros, and do any other necessary fixup for
 // the target platform. The end result is that multiple libraries can funnel
 // events through to a shared trace event collector.
@@ skipping 424 matching lines @@
 #define TRACE_EVENT_COPY_FINISH2(category, name, id, arg1_name, arg1_val, \
         arg2_name, arg2_val) \
     INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FINISH, \
         category, name, id, TRACE_EVENT_FLAG_HAS_ID | TRACE_EVENT_FLAG_COPY, \
         arg1_name, arg1_val, arg2_name, arg2_val)
 
 
 ////////////////////////////////////////////////////////////////////////////////
 // Implementation specific tracing API definitions.
 
+// Get a pointer to the enabled state of the given trace category. Only
+// long-lived literal strings should be given as the category name. The returned
+// pointer can be held permanently in a local static for example. If the
+// unsigned char is non-zero, tracing is enabled. If tracing is enabled,
+// TRACE_EVENT_API_ADD_TRACE_EVENT can be called. It's OK if tracing is disabled
+// between the load of the tracing state and the call to
+// TRACE_EVENT_API_ADD_TRACE_EVENT, because this flag only provides an early out
+// for best performance when tracing is disabled.
 // const unsigned char*
 //     TRACE_EVENT_API_GET_CATEGORY_ENABLED(const char* category_name)
 #define TRACE_EVENT_API_GET_CATEGORY_ENABLED \
     base::debug::TraceLog::GetCategoryEnabled
 
-// Returns the threshold_begin_id used by TRACE_IF_LONGER_THAN macros.
+// Add a trace event to the platform tracing system. Returns thresholdBeginId
+// for use in a corresponding end TRACE_EVENT_API_ADD_TRACE_EVENT call.
 // int TRACE_EVENT_API_ADD_TRACE_EVENT(
 //                    char phase,
 //                    const unsigned char* category_enabled,
 //                    const char* name,
 //                    unsigned long long id,
 //                    int num_args,
 //                    const char** arg_names,
 //                    const unsigned char* arg_types,
 //                    const unsigned long long* arg_values,
 //                    int threshold_begin_id,
 //                    long long threshold,
 //                    unsigned char flags)
 #define TRACE_EVENT_API_ADD_TRACE_EVENT \
     base::debug::TraceLog::GetInstance()->AddTraceEvent
 
-// void TRACE_EVENT_API_ADD_COUNTER_EVENT(
-//                    const unsigned char* category_enabled,
-//                    const char* name,
-//                    unsigned long long id,
-//                    const char* arg1_name, int arg1_val,
-//                    const char* arg2_name, int arg2_val,
-//                    unsigned char flags)
-#define TRACE_EVENT_API_ADD_COUNTER_EVENT \
-    base::debug::TraceLog::GetInstance()->AddCounterEvent
-
-// Mangle |pointer| with a process ID hash so that if |pointer| occurs on more
-// than one process, it will not collide in the trace data.
+// Mangle pointer with a hash so that if it occurs on more than one process,
+// it will not collide in the trace data. Pass the returned value to
+// TRACE_EVENT_API_ADD_TRACE_EVENT as the id parameter.
 // unsigned long long TRACE_EVENT_API_GET_ID_FROM_POINTER(void* pointer)
 #define TRACE_EVENT_API_GET_ID_FROM_POINTER \
     base::debug::TraceLog::GetInstance()->GetInterProcessID
 
 ////////////////////////////////////////////////////////////////////////////////
 
 // Implementation detail: trace event macros create temporary variables
 // to keep instrumentation overhead low. These macros give each temporary
 // variable a unique name based on the line number to prevent name collissions.
 #define INTERNAL_TRACE_EVENT_UID3(a,b) \
@@ skipping 105 matching lines @@
 // Specify these values when the corresponding argument of AddTraceEvent is not
 // used.
 const int kZeroNumArgs = 0;
 const int kNoThreshholdBeginId = -1;
 const long long kNoThresholdValue = 0;
 const unsigned long long kNoEventId = 0;
 
 // TraceID encapsulates an ID that can either be an integer or pointer. Pointers
 // are mangled with the Process ID so that they are unlikely to collide when the
 // same pointer is used on different processes.
-class BASE_EXPORT TraceID {
+class TraceID {
  public:
   explicit TraceID(void* rhs) :
       data_(TRACE_EVENT_API_GET_ID_FROM_POINTER(rhs)) {}
   explicit TraceID(unsigned long long rhs) : data_(rhs) {}
   explicit TraceID(unsigned long rhs) : data_(rhs) {}
   explicit TraceID(unsigned int rhs) : data_(rhs) {}
   explicit TraceID(unsigned short rhs) : data_(rhs) {}
   explicit TraceID(unsigned char rhs) : data_(rhs) {}
   explicit TraceID(long long rhs) :
       data_(static_cast<unsigned long long>(rhs)) {}
@@ skipping 201 matching lines @@
     const char* name;
     int threshold_begin_id;
   };
   Data* p_data_;
   Data data_;
 };
 
 }  // namespace trace_event_internal
 
 #endif  // BASE_DEBUG_TRACE_EVENT_H_