Make flow event traces disabled-by-default, and rename "ipc" and "task" categories to "toplevel"

base/debug/trace_event_memory.cc

 // 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 "base/debug/trace_event_memory.h"
 
 #include "base/debug/leak_annotations.h"
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 391 matching lines @@
   const std::string kSingleQuote = "'";
   for (size_t t = 4; t < tokens.size(); t += 2) {
     // Casting strings into pointers is ugly but otherwise tcmalloc would need
     // to gain a special output serializer just for pseudo-stacks.
     const char* trace_category = StringFromHexAddress(tokens[t]);
     DCHECK_LT(t + 1, tokens.size());
     const char* trace_name = StringFromHexAddress(tokens[t + 1]);
 
     // TODO(jamescook): Report the trace category and name separately to the
     // trace viewer and allow it to decide what decorations to apply. For now
-    // just hard-code a decoration for posted tasks.
+    // just hard-code a decoration for posted tasks (toplevel).
     std::string trace_string(trace_name);
-    if (!strcmp(trace_category, "task"))
+    if (!strcmp(trace_category, "toplevel"))
       trace_string.append("->PostTask");
 
     // Some trace name strings have double quotes, convert them to single.
     ReplaceChars(trace_string, "\"", kSingleQuote, &trace_string);
 
     output->append(trace_string);
 
     // Trace viewer expects a trailing space.
     output->append(" ");
   }
   output->append("\"}");
   return true;
 }
 
 const char* StringFromHexAddress(const std::string& hex_address) {
   uint64 address = 0;
   if (!base::HexStringToUInt64(hex_address, &address))
     return "error";
   if (!address)
     return "null";
   // Note that this cast handles 64-bit to 32-bit conversion if necessary.
   return reinterpret_cast<const char*>(address);
 }
 
 }  // namespace debug
 }  // namespace base