Gtk3: Refactor GtkButtonImageSource::GetImageForScale
This CL refactors GetImageForScale() on Gtk3 so no widget gets created. Only
a GtkStyleContext is needed.
In addition, it adds GtkStateFlagFocused to the style context if |focus_| is true.
This fixes focused button rendering on Ambiance, which doesn't use a focus
rectangle, but instead changes the button's border directly.
BUG=695357
R=erg@chromium.org
Review-Url: https://codereview.chromium.org/2715153002
Cr-Commit-Position: refs/heads/master@{#453292}
4 files changed
