I finally found solutions to my two problems, look the following
for mailto tag to use gmail, {check this link} (can't post link yet)
try
- Open your javascript console
- type
navigator.registerProtocolHandler("mailto",
"(1)mail.google.com/mail/?extsrc=mailto&url=%s",
"Gmail");
- Accept the confirmation from the browser.
(I found solution from Paul Irish but can't post link. If someone find the link please edit my post. I'll do it as soon as I can)
Also for pdf files. I really think all pdf readers are more or less crap in Linux, to heavy or light but you just can only read from it (you don't have search options or table of contents), anyway I downloaded this from the store: check pdf.js or html5 pdf viewer on chrome/chromium store both are the pretty the same. Thoses are perfectly doing things as I expected
Hope it helps you too.