Add --trace-rotate-startup-file option and store unsaved trace data on exit.

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 6aef2203bc85693c3124773b35134905b5bf99c7..5a557a93a579d8dfa0165e458010b7144d3bde93 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -43,6 +43,7 @@
 #include "content/browser/speech/speech_recognition_manager_impl.h"
 #include "content/browser/startup_task_runner.h"
 #include "content/browser/time_zone_monitor.h"
+#include "content/browser/tracing/add_new_file_index.h"
 #include "content/browser/webui/content_web_ui_controller_factory.h"
 #include "content/browser/webui/url_data_manager.h"
 #include "content/public/browser/browser_main_parts.h"
@@ -901,6 +902,10 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   }
 }
 
+void BrowserMainLoop::StopStartupTracingTimer() {
+  startup_trace_timer_.Stop();
+}
+
 void BrowserMainLoop::InitializeMainThread() {
   TRACE_EVENT0("startup", "BrowserMainLoop::InitializeMainThread");
   const char* kThreadName = "CrBrowserMain";
@@ -1121,6 +1126,11 @@ void BrowserMainLoop::InitStartupTracing(const CommandLine& command_line) {
 #endif
   }
 
+  if (command_line.HasSwitch(switches::kTraceRotateStartupFile))
+    trace_file = AddNewLogFileIndex(trace_file);
+
+  startup_trace_file_ = trace_file;
+
   std::string delay_str = command_line.GetSwitchValueASCII(
       switches::kTraceStartupDuration);
   int delay_secs = 5;
@@ -1130,17 +1140,16 @@ void BrowserMainLoop::InitStartupTracing(const CommandLine& command_line) {
     delay_secs = 5;
   }
 
-  BrowserThread::PostDelayedTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(&BrowserMainLoop::EndStartupTracing,
-                 base::Unretained(this), trace_file),
-      base::TimeDelta::FromSeconds(delay_secs));
+  startup_trace_timer_.Start(FROM_HERE,
+                             base::TimeDelta::FromSeconds(delay_secs),
+                             this,
+                             &BrowserMainLoop::EndStartupTracing);
 }
 
-void BrowserMainLoop::EndStartupTracing(const base::FilePath& trace_file) {
+void BrowserMainLoop::EndStartupTracing() {
   is_tracing_startup_ = false;
   TracingController::GetInstance()->DisableRecording(
-      trace_file, base::Bind(&OnStoppedStartupTracing));
+      startup_trace_file_, base::Bind(&OnStoppedStartupTracing));
 }
 
 }  // namespace content