DevTools: enable target domain handler on the browser target, make browser target non-discoverable.

chrome/browser/devtools/chrome_devtools_manager_delegate.cc

Index: chrome/browser/devtools/chrome_devtools_manager_delegate.cc
diff --git a/chrome/browser/devtools/chrome_devtools_manager_delegate.cc b/chrome/browser/devtools/chrome_devtools_manager_delegate.cc
index a438fc43036256e924e81a26a7cbe89cc6164807..a486141148b5836a081ebab05f066e4173219a9f 100644
--- a/chrome/browser/devtools/chrome_devtools_manager_delegate.cc
+++ b/chrome/browser/devtools/chrome_devtools_manager_delegate.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/devtools/chrome_devtools_manager_delegate.h"
 
+#include "base/guid.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
@@ -166,6 +167,11 @@ std::string ChromeDevToolsManagerDelegate::GetFrontendResource(
   return content::DevToolsFrontendHost::GetFrontendResource(path).as_string();
 }
 
+std::string ChromeDevToolsManagerDelegate::GetBrowserTargetGUID() {
+  CR_DEFINE_STATIC_LOCAL(std::string, guid, (base::GenerateGUID()));
+  return guid;
+}
+
 void ChromeDevToolsManagerDelegate::DevToolsAgentHostAttached(
     content::DevToolsAgentHost* agent_host) {
   network_protocol_handler_->DevToolsAgentStateChanged(agent_host, true);