android4.0鼠标右键返回功能

鼠标右键返回功能。
在frameworksbaseservicesinputInputReader.cpp文件下修改

uint32_t CursorButtonAccumulator::getButtonState() const {
    uint32_t result = 0;
    if (mBtnLeft) {
        result |= AMOTION_EVENT_BUTTON_PRIMARY;
    }
    if (mBtnRight) {
        result |= AMOTION_EVENT_BUTTON_BACK;
    }
    if (mBtnMiddle) {
        result |= AMOTION_EVENT_BUTTON_TERTIARY;
    }
    if (mBtnBack || mBtnSide) {
        result |= AMOTION_EVENT_BUTTON_BACK;
    }
    if (mBtnForward || mBtnExtra) {
        result |= AMOTION_EVENT_BUTTON_FORWARD;
    }
    return result;