GitLab

Convert the code in pdf.js to an object

This is a refactoring of the code in pdf.js, moving the code into a PDFViewer object. This
will make it more testable and usable by other classes that will be added later.

BUG=303491

Review URL: https://codereview.chromium.org/223363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@262917 0039d316-1c4b-4281-b951-d872f2087c98