Selecting 'alt+left arrow' key in PDF does not move to previous url page. similarly...

Selecting 'alt+left arrow' key in PDF does not move to previous url page. similarly 'alt+right arrow' key in PDF does not move to next url page.

Currently alt+arrow, ctrl+arrow,shift+arrow work like when
user select just arrow key, so with in the pdf file movement happen.
That is wrong.
It should be like:
1.Page should move up with in PDF when
 -Selecting Shift+Spacebar.
 -Selecting Pageup key.
 -Selecting only Left Arrow Key.
2.Page should move down with in PDF when
 -Selecting Spacebar.
 -Selecting Pagedown key.
 -Selecting only Right Arrow Key.

Changes added so that alt+ arrow key should have default behavior
that is moving to previous or next url.

BUG=75089

Review URL: https://codereview.chromium.org/802083002

Cr-Commit-Position: refs/heads/master@{#308511}