Google says that changes will take place in three main phases over the 14 months from April 2018.
Gmail online service will show a message warning about the termination of support for Chrome browser older versions. Due to significant changes relating to safety you have to download the 55-th Chrome update to continue using mail services.
PDFium is a component of the Chrome web browser designed to display PDF documents. The vulnerability has been found in it, which allows to include dangerous code into a PDF file, and execute code by simply viewing a PDF.