Allow to start only one instance of log listener and crash watcher

Summary:
Changelog: Allow only a single crash watcher and a single log listener per device. Start log listener and crash watcher for every device upon connection. Remove commands to start/stop them externally.

Monitored CPU load for a physical Android device with the log listener on and off. Did not notice any real difference.

Resolved crashing adbkit-logcat by forcing the usage of 2.0.1. A proper fix would be to unify babel transforms for browser flipper and electron flipper, but we might re-think how we distribute flipper in the next half, so a simple hot fix might be a better use of time and resources.

Reviewed By: mweststrate

Differential Revision: D33132506

fbshipit-source-id: 39d422682a10a64830ac516e30f43f32f416819d

desktop/flipper-server-core/src/devices/ServerDevice.tsx

@@ -8,6 +8,7 @@
  */
 
 import {DeviceDescription, DeviceLogEntry} from 'flipper-common';
+import {DeviceListener, NoopListener} from '../utils/DeviceListener';
 import {FlipperServerImpl} from '../FlipperServerImpl';
 
 export abstract class ServerDevice {
@@ -17,6 +18,11 @@ export abstract class ServerDevice {
 
   protected stopCrashWatcherCb?: () => void;
 
+  readonly logListener: DeviceListener = new NoopListener(() => this.connected);
+  readonly crashWatcher: DeviceListener = new NoopListener(
+    () => this.connected,
+  );
+
   constructor(flipperServer: FlipperServerImpl, info: DeviceDescription) {
     this.flipperServer = flipperServer;
     this.info = info;
@@ -38,28 +44,8 @@ export abstract class ServerDevice {
    */
   disconnect(): void {
     this.connected = false;
-  }
-
-  startLogging() {
-    // to be subclassed
-  }
-
-  stopLogging() {
-    // to be subclassed
-  }
-
-  startCrashWatcher() {
-    this.stopCrashWatcherCb = this.startCrashWatcherImpl?.();
-  }
-
-  protected startCrashWatcherImpl(): () => void {
-    // to be subclassed
-    return () => {};
-  }
-
-  stopCrashWatcher() {
-    this.stopCrashWatcherCb?.();
-    this.stopCrashWatcherCb = undefined;
+    this.logListener.stop();
+    this.crashWatcher.stop();
   }
 
   async screenshotAvailable(): Promise<boolean> {