Turn on DevTools Profiler....

chrome/renderer/render_process.cc

 // Copyright (c) 2006-2008 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 "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <objidl.h>
 #include <mlang.h>
@@ skipping 82 matching lines @@
 #endif
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kJavaScriptFlags)) {
     webkit_glue::SetJavaScriptFlags(
       command_line.GetSwitchValue(switches::kJavaScriptFlags));
   }
 
   if (!command_line.HasSwitch(switches::kDisableOutOfProcessDevTools)) {
     // Out of process dev tools rely upon auto break behavior.
-    webkit_glue::SetJavaScriptFlags(L"--debugger-auto-break");
+    webkit_glue::SetJavaScriptFlags(L"--debugger-auto-break"
+                                    // Enable lazy in-memory profiling.
+                                    L" --prof --prof-lazy --logfile=*");
   }
 
   if (command_line.HasSwitch(switches::kEnableWatchdog)) {
     // TODO(JAR): Need to implement renderer IO msgloop watchdog.
   }
 
   if (command_line.HasSwitch(switches::kDumpHistogramsOnExit)) {
     StatisticsRecorder::set_dump_on_exit(true);
   }
 
@@ skipping 145 matching lines @@
 }
 
 void RenderProcess::ClearTransportDIBCache() {
   for (size_t i = 0; i < arraysize(shared_mem_cache_); ++i) {
     if (shared_mem_cache_[i]) {
       FreeTransportDIB(shared_mem_cache_[i]);
       shared_mem_cache_[i] = NULL;
     }
   }
 }