Once Per-Monitor DPI is enabled for Chrome, WM_DPICHANGED will be fired by the
Windows manager to let Chrome now the DPI for its HWND has changed and suggest
a new size and location for the Chrome Window based off of the new DPI.

BUG=426656

Review-Url: https://codereview.chromium.org/2093993003
Cr-Commit-Position: refs/heads/master@{#402353}