This week, Vivo launched the Vivo X21 in China with the Qualcomm Snapdragon 660 system-on-chip. On the same day, Oppo made the Oppo R15 official. On Thursday, Vivo launched a lower-end version of the X21, the Vivo V9, in Thailand. On Friday, the device was officially launched in India - one of Vivo's major international...