LocationBar color doesn't update when changing theme

[petemill]

Steps to reproduce

• Go to Settings > Appearance
• Change theme between light and dark

Expected

All toolbar colors, including location bar colors change immediately

Actual

LocationBar colors do not change until something else updates the location bar (e.g. click)

Notes

Needs to observe the prefs change, or the theme change (if we had such an observer), and update the colors. This is not built-in to chromium since an extension theme cannot change the location bar colors.

[simonhong]

As you expected, I think we should override LocationBarView::OnThemeChanged() and do similar thing in OnNativeThemeChanged().

[srirambv]

@petemill just mouse over is enough to change the colour

Also icons and buttons looks hidden when colour scheme is changed

[petemill]

Closing #982 as duplicate which states

brave/brave-core#407introduces switching NativeTheme between dark and light when our theme service mode is changed between dark and light. However, this does not change immediately when the user changes between light and dark via preferences. The user must switch tabs before these colors are re-calculated.

Similarly for GetOmniboxColor which is also sync'ed to light and dark choice, though that re-paints when the LocationBar is hovered.

Both should observe the theme mode preference and change immediately."

[LaurenWags]

Verification Pass with

Brave	0.55.5 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Mac OS X

Brave	0.55.5 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Windows 7

Verification Passed on

Brave	0.55.6 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Linux