GitLab

Adding CanMinimize() (like CanMaximize()) function to WidgetDelegate class.
So that ColorChooserView or any other view inheriting WidgetDelegate, can
decide whether its window can show minimize button.

BUG=365768

R=sadrul@chromium.org

TEST=
1. Go to a page with <input type=color>. Here is one http://jsbin.com/yotasure/1
2. Click on the color input button to bring up the color picker window and observe
3. Color picker window should not have minimize button.

Review URL: https://codereview.chromium.org/567463002

Cr-Commit-Position: refs/heads/master@{#295919}