Make DevToolsManager a singleton, remove it from ContentBrowserClient

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 018acf531a8df35c161f6de99f40f1cef1686b5e..2ca97abfbf848fa497b4f9d84f2dadd08b5157dc 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -1008,10 +1008,6 @@ MHTMLGenerationManager*
   return g_browser_process->mhtml_generation_manager();
 }
 
-DevToolsManager* ChromeContentBrowserClient::GetDevToolsManager() {
-  return g_browser_process->devtools_manager();
-}
-
 net::NetLog* ChromeContentBrowserClient::GetNetLog() {
   return g_browser_process->net_log();
 }