I am not 100% sure if it is a bug, but i am going to post the problem, and my solution here.
After update the system(64bit CLDG) by ,
emerge -auDN world
the flash does not work in chromium, it shows the following in terminal
/usr/lib64/nspluginwrapper/i386/linux/npviewer.bin: /usr/lib64/nspluginwrapper/i386/linux/npviewer.bin: cannot execute binary file
to solve this issue
emerge nspluginwrapper
For the flash, download 64bit adobe flash from adobe(search it on google…)
mkdir /usr/lib64/chromium-browser/plugins
copy libflashplayer.so /usr/lib64/chromium-browser/plugins
restart the chromium, it should work fine now