Implement backend for thread names and process names.

Added a new trace event phase 'M'/TRACE_EVENT_PHASE_METADATA,
which can become a general mechanism for adding metadata to traces.

The two M-type events that we then add are:
	{ph=M pid=<pid> name="process_name" args={ name="name of pid" }}
	{ph=M pid=<pid> tid=<tid> name="thread_name" args={ name="name of tid" }}

base::thread is instrumented to set names automatically. I will do a followon
changelist to add instrumentation to Chrome for its various processes and
threads.

Review URL: http://codereview.chromium.org/7495031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@95997 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 0 deletions

diff --git a/base/threading/platform_thread_mac.mm b/base/threading/platform_thread_mac.mm
index 7d59064..9894a1d 100644
--- a/base/threading/platform_thread_mac.mm
+++ b/base/threading/platform_thread_mac.mm
@@ -11,9 +11,12 @@
 #include <mach/thread_policy.h>
 
 #include "base/logging.h"
+#include "base/threading/thread_local.h"
 
 namespace base {
 
+static ThreadLocalPointer<char> current_thread_name;
+
 // If Cocoa is to be used on more than one thread, it must know that the
 // application is multithreaded.  Since it's possible to enter Cocoa code
 // from threads created by pthread_thread_create, Cocoa won't necessarily
@@ -37,6 +40,8 @@ void InitThreading() {
 
 // static
 void PlatformThread::SetName(const char* name) {
+  current_thread_name.Set(const_cast<char*>(name));
+
   // pthread_setname_np is only available in 10.6 or later, so test
   // for it at runtime.
   int (*dynamic_pthread_setname_np)(const char*);
@@ -54,6 +59,11 @@ void PlatformThread::SetName(const char* name) {
   dynamic_pthread_setname_np(shortened_name.c_str());
 }
 
+// static
+const char* PlatformThread::GetName() {
+  return current_thread_name.Get();
+}
+
 namespace {
 
 void SetPriorityNormal(mach_port_t mach_thread_id) {