ThreadWatcher - Added jankiness monitor for FILE thread.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
===================================================================
--- chrome/common/chrome_switches.cc	(revision 181723)
+++ chrome/common/chrome_switches.cc	(working copy)
@@ -202,19 +202,14 @@
 // string value, the 2 letter code from ISO 3166-1.
 const char kCountry[]                       = "country";
 
-// Causes the browser process to crash if browser threads are not responding
-// for the given number of seconds.
-const char kCrashOnHangSeconds[]            = "crash-on-hang-seconds";
-
 // Comma-separated list of BrowserThreads that cause browser process to crash
 // if the given browser thread is not responsive. UI,IO,DB,FILE,CACHE are the
 // list of BrowserThreads that are supported.
 //
 // For example:
-//    --crash-on-hang-threads=UI:3,IO:3 --> Crash the browser if UI or IO thread
-//                                          is not responsive and the number of
-//                                          browser threads that are responding
-//                                          is less than or equal to 3.
+//    --crash-on-hang-threads=UI:3:18,IO:3:18 --> Crash the browser if UI or IO
+//      is not responsive for 18 seconds and the number of browser threads that
+//      are responding is less than or equal to 3.
 const char kCrashOnHangThreads[]            = "crash-on-hang-threads";
 
 // Some platforms like ChromeOS default to empty desktop.