feat: netLog API for dynamic logging control (#13068)

* Introduce `net.{start|stop}Logging()`

- Slight regression right now as Electron won't automatically start logging net-logs at launch, will soon be fixed
- To implement callback for async controls

* Add `net.isLogging` & optional callback param for `net.stopLogging()`

* Fix small regression on --log-net-log

--log-net-log should work again

* Error on empty file path

* Only start with valid file path

* Remove unused var

* Allow setting log file path before URLRequestContextGetter starts logging

* Add net log tests

* Remove redundant checks

* Use brightray::NetLog

* Clean up code

* Should automatically stop listening

* 🎨 Attempt to fix styles

* Only run non-null callback

* Dump file to tmpdir

* Simplify net log spec

Spawned Electron process on Linux CI can fail to launch

* Separate netLog module

* Remove net logging test from net spec

* Add tests for netLog

* Fix header guard

* Clean up code

* Add netLog.currentlyLoggingPath

* Callback with filepath

* Add test for case when only .stopLogging() is called

* Add docs

* Reintroduce error on invalid arg

* Update copyright

* Update error message

* Juggle file path string types

atom/browser/api/atom_api_net_log.h

@@ -0,0 +1,42 @@
+// Copyright (c) 2018 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_BROWSER_API_ATOM_API_NET_LOG_H_
+#define ATOM_BROWSER_API_ATOM_API_NET_LOG_H_
+
+#include <string>
+#include "brightray/browser/net_log.h"
+#include "native_mate/wrappable.h"
+
+namespace atom {
+
+namespace api {
+
+class NetLog : public mate::Wrappable<NetLog> {
+ public:
+  static v8::Local<v8::Value> Create(v8::Isolate* isolate);
+
+  static void BuildPrototype(v8::Isolate* isolate,
+                             v8::Local<v8::FunctionTemplate> prototype);
+
+  void StartLogging(mate::Arguments* args);
+  bool IsCurrentlyLogging();
+  base::FilePath::StringType GetCurrentlyLoggingPath();
+  void StopLogging(mate::Arguments* args);
+
+ protected:
+  explicit NetLog(v8::Isolate* isolate);
+  ~NetLog() override;
+
+ private:
+  brightray::NetLog* net_log_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetLog);
+};
+
+}  // namespace api
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_API_ATOM_API_NET_LOG_H_