Adding shutdown tracing capabilities

content/browser/browser_main_runner.cc

Index: content/browser/browser_main_runner.cc
diff --git a/content/browser/browser_main_runner.cc b/content/browser/browser_main_runner.cc
index f97318a690657892c4676b1b1d454f9dd75f8a1b..bd44a2dda99c4012ac0204ab270cfbef9efec372 100644
--- a/content/browser/browser_main_runner.cc
+++ b/content/browser/browser_main_runner.cc
@@ -12,6 +12,7 @@
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "content/browser/browser_main_loop.h"
+#include "content/browser/browser_shutdown_profile_dumper.h"
 #include "content/browser/notification_service_impl.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/main_function_params.h"
@@ -122,22 +123,34 @@ class BrowserMainRunnerImpl : public BrowserMainRunner {
   }
 
   virtual void Shutdown() OVERRIDE {
-    DCHECK(initialization_started_);
-    DCHECK(!is_shutdown_);
-    g_exited_main_message_loop = true;
+    // The shutdown tracing got enabled in AttemptUserExit earlier, but someone
+    // needs to write the result to disc. For that a dumper needs to get created
+    // which will dump the traces to disc when it gets destroyed.
+    const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+    scoped_ptr<BrowserShutdownProfileDumper> profiler;
+    if (command_line.HasSwitch(switches::kTraceShutdown))
+      profiler.reset(new BrowserShutdownProfileDumper());
 
-    main_loop_->ShutdownThreadsAndCleanUp();
+    {
+      // The trace event has to stay between profiler creation and destruction.
+      TRACE_EVENT0("shutdown", "BrowserMainRunner");
+      DCHECK(initialization_started_);

[sky, 2013/09/05 00:00:14]

I would actually keep these three above your changes since they are general
preconditions.

[Mr4D (OOO till 08-26), 2013/09/05 00:13:40]

Done.

+      DCHECK(!is_shutdown_);
+      g_exited_main_message_loop = true;
 
-    ui::ShutdownInputMethod();
-#if defined(OS_WIN)
-    ole_initializer_.reset(NULL);
-#endif
+      main_loop_->ShutdownThreadsAndCleanUp();
+
+      ui::ShutdownInputMethod();
+  #if defined(OS_WIN)
+      ole_initializer_.reset(NULL);
+  #endif
 
-    main_loop_.reset(NULL);
+      main_loop_.reset(NULL);
 
-    notification_service_.reset(NULL);
+      notification_service_.reset(NULL);
 
-    is_shutdown_ = true;
+      is_shutdown_ = true;
+    }
   }
 
  protected: