[usecase-webapi] Improve WebSocket usecase

- Adjust the case with screen view

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 1, fail 0, block 0
Merge pull request #595 from yunxliu/yunxliu/misc/webSocket

[usecase-webapi] Improve WebSocket usecase