Fix Spacing in OmniboxResultView

OmniboxResultView's Widget was returning the default ThemeProvider. With the
layout parameters now themeable, this was leading to incorrect values being used
for layout.

OmniboxResultView has been updated to refer to LocationBarView's ThemeProvider
in order to get the appropriate values.

A TODO was added to review the dependency on LocaitonBarView. This will be
addressed when the omnibox suggestion popup is updated for Material Design.

TEST=Manual testing on device, ran interactive_ui_tests
BUG=515378

Review URL: https://codereview.chromium.org/1262413005

Cr-Commit-Position: refs/heads/master@{#341921}
1 file changed