MFH: r376780

www/chromium:

• install libpdf.so to enable the built-in PDF viewer [1]
• show memory usage of browser, GPU, individual plugins, and individual tabs in chrome://memory-redirect [2]
• bump PORTREVISION

Submitted by: Imre Vadász via GitHub [1,2]
Approved by: portmgr (unanswered, but needed for next MFH to align)