Remove unnecessary instrumentation for several jank bugs.

net/dns/single_request_host_resolver.cc

Index: net/dns/single_request_host_resolver.cc
diff --git a/net/dns/single_request_host_resolver.cc b/net/dns/single_request_host_resolver.cc
index 2c4b3aa19b9aaf9e193cafac1bb427fc883ff9a0..7974abafeef3518983a1d4604e3f5382c6f6d96c 100644
--- a/net/dns/single_request_host_resolver.cc
+++ b/net/dns/single_request_host_resolver.cc
@@ -8,7 +8,6 @@
 #include "base/bind_helpers.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
-#include "base/profiler/scoped_tracker.h"
 #include "net/base/net_errors.h"
 
 namespace net {
@@ -64,11 +63,6 @@ void SingleRequestHostResolver::Cancel() {
 }
 
 void SingleRequestHostResolver::OnResolveCompletion(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/436634 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "436634 SingleRequestHostResolver::OnResolveCompletion"));
-
   DCHECK(cur_request_);
   DCHECK_EQ(false, cur_request_callback_.is_null());