Tracing for NavigationHandle lifetime and state.

content/public/browser/navigation_throttle.h

Index: content/public/browser/navigation_throttle.h
diff --git a/content/public/browser/navigation_throttle.h b/content/public/browser/navigation_throttle.h
index 109a2fc4760f79c66796aa76b14fc135b3e07301..eb079fa40f64618dea62f18e6cb89bbab9573f7a 100644
--- a/content/public/browser/navigation_throttle.h
+++ b/content/public/browser/navigation_throttle.h
@@ -77,6 +77,10 @@ class CONTENT_EXPORT NavigationThrottle {
   // asynchronously.
   virtual ThrottleCheckResult WillProcessResponse();
 
+  // Returns the name of the throttle for logging purposes. It must not return
+  // nullptr.
+  virtual const char* GetNameForLogging() = 0;
+
   // The NavigationHandle that is tracking the information related to this
   // navigation.
   NavigationHandle* navigation_handle() const { return navigation_handle_; }