Add performance tracing for PlatformThread and parts of the video code.

webrtc/base/platform_thread.cc

Index: webrtc/base/platform_thread.cc
diff --git a/webrtc/base/platform_thread.cc b/webrtc/base/platform_thread.cc
index b17c30105a3ce0f0637663d8fcafeb4d3ec82fcf..b4724b99e951d486c2afa3003a7e2445b487cffe 100644
--- a/webrtc/base/platform_thread.cc
+++ b/webrtc/base/platform_thread.cc
@@ -13,6 +13,7 @@
 #include "webrtc/base/atomicops.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/timeutils.h"
+#include "webrtc/base/trace_event.h"
 
 #if defined(WEBRTC_LINUX)
 #include <sys/prctl.h>
@@ -235,6 +236,8 @@ void PlatformThread::Run() {
 #endif
 
   do {
+    TRACE_EVENT1("webrtc", "PlatformThread::Run", "name", name_.c_str());
+
     // The interface contract of Start/Stop is that for a successful call to
     // Start, there should be at least one call to the run function.  So we
     // call the function before checking |stop_|.