DevTools: introduce --custom-devtools-frontend flag.

chrome/common/url_constants.cc

Index: chrome/common/url_constants.cc
diff --git a/chrome/common/url_constants.cc b/chrome/common/url_constants.cc
index e9f785106edd22e666ec107636a759684e1c5a05..b87ee5eda44d4f8091718d911a4243f85ab9aff7 100644
--- a/chrome/common/url_constants.cc
+++ b/chrome/common/url_constants.cc
@@ -39,6 +39,8 @@ const char kChromeUIConstrainedHTMLTestURL[] = "chrome://constrained-test/";
 const char kChromeUICrashesURL[] = "chrome://crashes/";
 const char kChromeUICreditsURL[] = "chrome://credits/";
 const char kChromeUIDevicesURL[] = "chrome://devices/";
+const char kChromeUIDevToolsCustomURL[] =
+    "chrome-devtools://devtools/custom/inspector.html";
 const char kChromeUIDevToolsURL[] =
     "chrome-devtools://devtools/bundled/inspector.html";
 const char kChromeUIDomainReliabilityInternalsURL[] =
@@ -180,6 +182,7 @@ const char kChromeUIDeviceLogHost[] = "device-log";
 const char kChromeUIDevicesHost[] = "devices";
 const char kChromeUIDevToolsHost[] = "devtools";
 const char kChromeUIDevToolsBundledPath[] = "bundled";
+const char kChromeUIDevToolsCustomPath[] = "custom";
 const char kChromeUIDevToolsRemotePath[] = "remote";
 const char kChromeUIDNSHost[] = "dns";
 const char kChromeUIDomainReliabilityInternalsHost[] =