Add --trace-rotate-startup-file option and store unsaved trace data on exit.

content/public/common/content_switches.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 "content/public/common/content_switches.h"
 
 #include "base/command_line.h"
 
 namespace switches {
 
@@ skipping 844 matching lines @@
 
 // If supplied, sets the file which startup tracing will be stored into, if
 // omitted the default will be used "chrometrace.log" in the current directory.
 // Has no effect unless --trace-startup is also supplied.
 // Example: --trace-startup --trace-startup-file=/tmp/trace_event.log
 // As a special case, can be set to 'none' - this disables automatically saving
 // the result to a file and the first manually recorded trace will then receive
 // all events since startup.
 const char kTraceStartupFile[]              = "trace-startup-file";
 
-
+// Add numeric suffix to trace-startup-file name to create new trace file
+// on each start. First unused suffix will be used:
+// trace_event.log.0 , trace_event.log.1 , etc.
+const char kTraceRotateStartupFile[] = "trace-rotate-startup-file";
 
 // Prioritizes the UI's command stream in the GPU process
 extern const char kUIPrioritizeInGpuProcess[] =
     "ui-prioritize-in-gpu-process";
 
 // Overrides the preferred discardable memory implementation.
 const char kUseDiscardableMemory[] = "use-discardable-memory";
 
 // Bypass the media stream infobar by selecting the default device for media
 // streams (e.g. WebRTC). Works with --use-fake-device-for-media-stream.
@@ skipping 102 matching lines @@
 
 // Disables support for Core Animation plugins. This is triggered when
 // accelerated compositing is disabled. See http://crbug.com/122430 .
 const char kDisableCoreAnimationPlugins[] =
     "disable-core-animation-plugins";
 #endif
 
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches