LONDON (BBC) -  Google has announced a low-cost competitor to Apple TV - a “dongle” device called Chromecast. The dongle is plugged into a television’s HDMI port, and allows users to stream media from smartphones, tablets and computers. Launching immediately in the US, the device will cost $35 (£23). There is as yet no word on international launches. Google also announced an upgraded Nexus 7 tablet, the first to run the new version of the Android system.