ThemeData's accent properties have been deprecated

Application theme

[ThemeData][] values no longer need to specify accentColor, accentColorBrightness, accentIconTheme, or accentTextTheme.

To configure the appearance of the material components in about the same way as before, specify the color scheme's secondary color instead of accentColor.

Code before migration:

MaterialApp(
  theme: ThemeData(accentColor: myColor),
  // ...
);

Code after migration:

final ThemeData theme = ThemeData();
MaterialApp(
  theme: theme.copyWith(
    colorScheme: theme.colorScheme.copyWith(secondary: myColor),
  ),
  //...
)

accentColor

The closest backwards compatible [ColorScheme][] color is [ColorScheme.secondary][]. To hew most closely to the latest Material Design guidelines one can substitute ColorScheme.primary instead. If a contrasting color is needed then use [ColorScheme.onSecondary][].

Custom components that used to look up the theme's accentColor, can look up the ColorScheme.secondary instead.

Code before migration:

Color myColor = Theme.of(context).accentColor;

Code after migration:

Color myColor = Theme.of(context).colorScheme.secondary;

accentColorBrightness

The static [ThemeData.estimateBrightnessForColor()][] method can be used to compute the brightness of any color.

accentTextTheme

This was white [TextStyle]s for dark themes, black TextStyles for light themes. In most cases textTheme can be used instead. A common idiom was to refer to one TextStyle from accentTextTheme, since the text style's color was guaranteed to contrast well with the accent color (now ColorScheme.secondaryColor). To get the same result now, specify the text style's color as ColorScheme.onSecondary:

Code before migration:

TextStyle style = Theme.of(context).accentTextTheme.headline1;

Code after migration:

final ThemeData theme = Theme.of(context);
TextStyle style = theme.textTheme.headline1.copyWith(
  color: theme.colorScheme.onSecondary,
)

accentIconTheme

This property had only been used to configure the color of icons within a [FloatingActionButton][]. It's now possible to configure the icon color directly or with the [FloatingActionButtonThemeData][]. See [FloatingActionButton and ThemeData's accent properties][].