Support WebSocket in WebRequest API.

extensions/common/api/web_request.json

Index: extensions/common/api/web_request.json
diff --git a/extensions/common/api/web_request.json b/extensions/common/api/web_request.json
index 1fe511ae69844e8e0b1ada7211e72dd3763a2476..2aeecc85e22d300d029203d4fa37e4f0c55aef8e 100644
--- a/extensions/common/api/web_request.json
+++ b/extensions/common/api/web_request.json
@@ -111,7 +111,7 @@
           "redirectUrl": {
             "type": "string",
             "optional": true,
-            "description": "Only used as a response to the onBeforeRequest and onHeadersReceived events. If set, the original request is prevented from being sent/completed and is instead redirected to the given URL. Redirections to non-HTTP schemes such as data: are allowed. Redirects initiated by a redirect action use the original request method for the redirect, with one exception: If the redirect is initiated at the onHeadersReceived stage, then the redirect will be issued using the GET method."
+            "description": "Only used as a response to the onBeforeRequest and onHeadersReceived events. If set, the original request is prevented from being sent/completed and is instead redirected to the given URL. Redirections to non-HTTP schemes such as <code>data:</code> are allowed. Redirects initiated by a redirect action use the original request method for the redirect, with one exception: If the redirect is initiated at the onHeadersReceived stage, then the redirect will be issued using the GET method. Redirects from URLs with <code>ws://</code> and <code>wss://</code> schemes are <b>ignored</b>."
           },
           "requestHeaders": {
             "$ref": "HttpHeaders",