NetworkService: Destroy NetworkContexts on NetworkService teardown.

content/network/network_context.h

Index: content/network/network_context.h
diff --git a/content/network/network_context.h b/content/network/network_context.h
index a4dd42c2b6808c637e36c76dc9dc485e275ca189..b6b5332f14658884eb0434f1c44097264925e3d6 100644
--- a/content/network/network_context.h
+++ b/content/network/network_context.h
@@ -22,11 +22,13 @@ class URLRequestContext;
 }
 
 namespace content {
+class NetworkService;
 class URLLoaderImpl;
 
 class NetworkContext : public mojom::NetworkContext {
  public:
-  NetworkContext(mojom::NetworkContextRequest request,
+  NetworkContext(NetworkService* network_service,
+                 mojom::NetworkContextRequest request,
                  mojom::NetworkContextParamsPtr params);
   ~NetworkContext() override;
 
@@ -47,9 +49,18 @@ class NetworkContext : public mojom::NetworkContext {
   void HandleViewCacheRequest(const GURL& url,
                               mojom::URLLoaderClientPtr client) override;
 
+  // Called when the associated NetworkService is going away. Guaranteed to
+  // destroy NetworkContext's URLRequestContext.
+  void Cleanup();
+
  private:
   NetworkContext();
 
+  // On connection errors the NetworkContext destroys itself.
+  void OnConnectionError();
+
+  NetworkService* const network_service_;
+
   std::unique_ptr<net::URLRequestContext> url_request_context_;
 
   // Put it below |url_request_context_| so that it outlives all the