Don't prepare platform N times if N files have been changed.

Move platform preparation out of beforeBatchLiveSyncAction and call it once
before processing changed files.

Author: hdeshev

services/usb-livesync-service-base.ts

@@ -149,6 +149,7 @@ export class UsbLiveSyncServiceBase implements IUsbLiveSyncServiceBase {
 					this.$logger.trace("Syncing %s", filesToSync.join(", "));
 					this.$dispatcher.dispatch( () => {
 						return (() => {
+							this.preparePlatformForSync(platform);
 							this.syncCore(platform, filesToSync, appIdentifier, projectFilesPath, platformSpecificLiveSyncServices, notInstalledAppOnDeviceAction, beforeLiveSyncAction).wait();
 						}).future<void>()();
 					});
@@ -161,6 +162,9 @@ export class UsbLiveSyncServiceBase implements IUsbLiveSyncServiceBase {
 		}).future<void>()());
 	}
 
+	protected preparePlatformForSync(platform: string) {
+	}
+
 	private isFileExcluded(path: string, exclusionList: string[], projectDir: string): boolean {
 		return !!_.find(exclusionList, (pattern) => minimatch(path, pattern, { nocase: true }));
 	}