Set process phases in the StackSamplingProfiler.

content/public/browser/browser_main_parts.h

Index: content/public/browser/browser_main_parts.h
diff --git a/content/public/browser/browser_main_parts.h b/content/public/browser/browser_main_parts.h
index 8b41253e0574dda3bba78cbea10c0dd9af315a70..db3ecb2e8133454c850923979866e5d737c149e0 100644
--- a/content/public/browser/browser_main_parts.h
+++ b/content/public/browser/browser_main_parts.h
@@ -91,6 +91,9 @@ class CONTENT_EXPORT BrowserMainParts {
   // Called as the very last part of shutdown, after threads have been
   // stopped and destroyed.
   virtual void PostDestroyThreads() {}
+
+  // Called when shutdown is about to begin.
+  virtual void PreShutdown() {}

[jochen (gone - plz use gerrit), 2017/01/12 08:35:02]

nit. can you move that up to before PostDestroyThreads, so the methods are in
the order of expected calls

[bcwhite, 2017/01/12 17:47:03]

Done.

 };
 
 }  // namespace content