Instrument some of the exit paths likely to suffer hangs.

chrome/browser/lifetime/application_lifetime.cc

Index: chrome/browser/lifetime/application_lifetime.cc
diff --git a/chrome/browser/lifetime/application_lifetime.cc b/chrome/browser/lifetime/application_lifetime.cc
index ddac0049acc86145e0d090d0bf48d5395a7acfc3..c7d4fb9ec6990ddca6c611a013893c68ddc0be6f 100644
--- a/chrome/browser/lifetime/application_lifetime.cc
+++ b/chrome/browser/lifetime/application_lifetime.cc
@@ -48,6 +48,7 @@
 
 #if defined(OS_WIN)
 #include "base/win/win_util.h"
+#include "components/browser_watcher/exit_funnel.h"
 #endif
 
 namespace chrome {
@@ -251,6 +252,11 @@ void ExitCleanly() {
 #endif
 
 void SessionEnding() {
+#if defined(OS_WIN)
+  browser_watcher::ExitFunnel funnel(kBrowserExitCodesRegistryPath,
+                                     base::GetCurrentProcessHandle());
+  funnel.RecordEvent(L"SessionEnding");
+#endif
   // This is a time-limited shutdown where we need to write as much to
   // disk as we can as soon as we can, and where we must kill the
   // process within a hang timeout to avoid user prompts.
@@ -276,6 +282,9 @@ void SessionEnding() {
       content::NotificationService::AllSources(),
       content::NotificationService::NoDetails());
 
+#if defined(OS_WIN)
+  funnel.RecordEvent(L"EndSession");
+#endif
   // Write important data first.
   g_browser_process->EndSession();
 
@@ -283,6 +292,12 @@ void SessionEnding() {
   base::win::SetShouldCrashOnProcessDetach(false);
 #endif
 
+#if defined(OS_WIN)
+  // KillProcess ought to terminate the process without further ado, so if
+  // execution gets to this point, presumably this is normal exit.
+  funnel.RecordEvent(L"KillProcess");
+#endif
+
   // On Windows 7 and later, the system will consider the process ripe for
   // termination as soon as it hides or destroys its windows. Since any
   // execution past that point will be non-deterministically cut short, we