Fix memory leak for WebRequest API with WebSocket

Bug: 898179
Change-Id: Ief4827898994347056aa731b30c42b9c496e5838
Reviewed-on: https://chromium-review.googlesource.com/c/1312186
Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604578}

extensions/browser/api/web_request/web_request_proxying_websocket.cc

@@ -48,7 +48,14 @@ WebRequestProxyingWebSocket::WebRequestProxyingWebSocket(
                           base::Unretained(this), net::ERR_FAILED));
 }
 
-WebRequestProxyingWebSocket::~WebRequestProxyingWebSocket() = default;
+WebRequestProxyingWebSocket::~WebRequestProxyingWebSocket() {
+  // This is important to ensure that no outstanding blocking requests continue
+  // to reference state owned by this object.
+  if (info_) {
+    ExtensionWebRequestEventRouter::GetInstance()->OnRequestWillBeDestroyed(
+        browser_context_, &info_.value());
+  }
+}
 
 void WebRequestProxyingWebSocket::AddChannelRequest(
     const GURL& url,