Add more instrumentation to track down jank.

chrome/browser/net/proxy_service_factory.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/net/proxy_service_factory.h"
 
 #include "base/command_line.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/threading/thread.h"
@@ skipping 104 matching lines @@
 
     // Parse the switch (it should be a positive integer formatted as decimal).
     int n;
     if (base::StringToInt(s, &n) && n > 0) {
       num_pac_threads = static_cast<size_t>(n);
     } else {
       LOG(ERROR) << "Invalid switch for number of PAC threads: " << s;
     }
   }
 
+  // TODO(eroman): Remove once crbug.com/454983 is fixed.
+  tracked_objects::ScopedTracker tracking_profile2(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "454983 ProxyServiceFactory::CreateProxyService_2"));
+
   net::ProxyService* proxy_service = NULL;
   if (use_v8) {
 #if defined(OS_IOS)
     NOTREACHED();
 #else
     net::DhcpProxyScriptFetcher* dhcp_proxy_script_fetcher;
 #if defined(OS_CHROMEOS)
     dhcp_proxy_script_fetcher =
         new chromeos::DhcpProxyScriptFetcherChromeos(context);
 #else
+    // TODO(eroman): Remove once crbug.com/454983 is fixed.
+    tracked_objects::ScopedTracker tracking_profile3(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "454983 ProxyServiceFactory::CreateProxyService_3"));

[mmenke, 2015/03/06 22:56:44]

optional nit:  Should this be just before the #ifdefined?  Even if we don't care
about ChromeOS, seems a little weird here.

Actually, there's so little between the start of "if (use_v8)" and this, seems
like this makes the most sense just after the if.

[eroman, 2015/03/06 23:02:43]

Done.

+
     net::DhcpProxyScriptFetcherFactory dhcp_factory;
     dhcp_proxy_script_fetcher = dhcp_factory.Create(context);
 #endif
 
+    // TODO(eroman): Remove once crbug.com/454983 is fixed.
+    tracked_objects::ScopedTracker tracking_profile3(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "454983 ProxyServiceFactory::CreateProxyService_3"));
+
     proxy_service = net::CreateProxyServiceUsingV8ProxyResolver(
         proxy_config_service,
         new net::ProxyScriptFetcherImpl(context),
         dhcp_proxy_script_fetcher,
         context->host_resolver(),
         net_log,
         network_delegate);
 #endif  // defined(OS_IOS)
   } else {
+    // TODO(eroman): Remove once crbug.com/454983 is fixed.
+    tracked_objects::ScopedTracker tracking_profile4(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "454983 ProxyServiceFactory::CreateProxyService_4"));
+
     proxy_service = net::ProxyService::CreateUsingSystemProxyResolver(
         proxy_config_service,
         num_pac_threads,
         net_log);
   }
 
   proxy_service->set_quick_check_enabled(quick_check_enabled);
 
   return proxy_service;
 }