Migrate datepicker to use final for messages.

PiperOrigin-RevId: 199236008

Author: TedSander

lib/material_datepicker/date_input.dart

@@ -358,7 +358,7 @@ class DateInputDirective implements OnDestroy {
     return thisYear;
   }
 
-  String get invalidDateMsg => Intl.message('Enter a date',
+  static final invalidDateMsg = Intl.message('Enter a date',
       name: 'invalidDateMsg',
       meaning: 'Error message',
       desc: 'Displayed when the user types text into a date input field which '

lib/material_datepicker/date_range_editor.dart

@@ -109,7 +109,7 @@ class DateRangeEditorComponent implements OnInit, AfterViewInit, Focusable {
 
   bool _supportsComparison = true;
 
-  String get comparisonHeaderMsg => Intl.message('Compare',
+  static final comparisonHeaderMsg = Intl.message('Compare',
       name: 'comparisonHeaderMsg',
       desc: 'Label for a toggle that turns time comparison on/off.');
 
@@ -503,43 +503,43 @@ class DateRangeEditorComponent implements OnInit, AfterViewInit, Focusable {
 
   String get customRangeDescription => formatRange(model.range.value);
 
-  String get navigateBeforeMsg => Intl.message('Previous date range',
+  static final navigateBeforeMsg = Intl.message('Previous date range',
       name: 'navigateBeforeMsg',
       meaning: 'Update the calendar display to show the previous time period.',
       desc: 'Label for control button which changes the range of dates shown in'
           'the calendar to the previous range of dates.');
 
-  String get navigateNextMsg => Intl.message('Next date range',
+  static final navigateNextMsg = Intl.message('Next date range',
       name: 'navigateNextMsg',
       meaning: 'Update the calendar display to show the next time period',
       desc: 'Label for control button which changes the range of dates shown in'
           'the calendar to the next range of dates.');
 
-  String get clearRangeMsg => Intl.message('Clear date range',
+  static final clearRangeMsg = Intl.message('Clear date range',
       name: 'DateRangeEditorComponent_clearRangeMsg',
       meaning: 'Clear the current range.',
       desc: 'Label for an option in the preset list at the left which '
           'clears the current selection.');
 
-  String get customRangeMsg => Intl.message('Custom',
+  static final customRangeMsg = Intl.message('Custom',
       name: 'DateRangeEditorComponent_customRangeMsg',
       meaning: 'Replace the current range with a Custom range that has the '
           'same endpoints.',
       desc: 'Label for an option in the preset list at the left which '
           'replaces the current selection with a "Custom" range.');
 
   // TODO(google): Check if some locales require text before the input.
-  String get daysToTodayMsg => Intl.message('days up to today',
+  static final daysToTodayMsg = Intl.message('days up to today',
       name: 'daysToTodayMsg',
       desc: 'Label for number input which changes the range of dates shown in'
           ' the calendar to [today - number, today].');
 
-  String get daysToYesterdayMsg => Intl.message('days up to yesterday',
+  static final daysToYesterdayMsg = Intl.message('days up to yesterday',
       name: 'daysToYesterdayMsg',
       desc: 'Label for number input which changes the range of dates shown in'
           ' the calendar to [yesterday - number, yesterday].');
 
-  String get rangeDisabledTooltip => Intl.message('No days available',
+  static final rangeDisabledTooltip = Intl.message('No days available',
       name: 'DateRangeEditorComponent_rangeDisabledTooltip',
       desc: 'Message that explains why a date range is invalid.');
 }

lib/material_datepicker/date_range_input.dart

@@ -198,11 +198,11 @@ class DateRangeInputComponent implements OnInit, OnDestroy {
   @Input()
   Date minDate = new Date(1000, DateTime.JANUARY, 1);
 
-  String get startDateMsg => Intl.message('Start date',
+  final startDateMsg = Intl.message('Start date',
       name: 'DateRangeInputComponent_startDateMsg',
       desc: 'ARIA label for the input specifying the start of the date range');
 
-  String get endDateMsg => Intl.message('End date',
+  final endDateMsg = Intl.message('End date',
       name: 'DateRangeInputComponent_endDateMsg',
       desc: 'ARIA label for the input specifying the end of the date range');
 }

lib/material_datepicker/material_date_range_picker.dart

@@ -550,14 +550,14 @@ class MaterialDateRangePickerComponent extends KeyboardHandlerMixin
     }
   }
 
-  String get cancelButtonMsg => Intl.message('Cancel',
+  static final cancelButtonMsg = Intl.message('Cancel',
       meaning: 'Button in a date picker',
       desc: 'Label for a "cancel" button -- abandon the current date selection '
           'and go back to whatever it was before the user opened the date picker');
 
   String get applyButtonMsg => applyButtonLabel ?? _applyButtonMsg;
 
-  String get _applyButtonMsg => Intl.message('Apply',
+  static final _applyButtonMsg = Intl.message('Apply',
       name: '_applyButtonMsg',
       meaning: 'Button in a date picker',
       desc: 'Label for an "Apply" button -- accept and apply the date range '
@@ -569,7 +569,7 @@ class MaterialDateRangePickerComponent extends KeyboardHandlerMixin
       args: [to],
       examples: const {'to': 'Jul 21, 2014 - Aug 3, 2015'});
 
-  String get _placeHolderMsg => Intl.message('Select a date range',
+  static final _placeHolderMsg = Intl.message('Select a date range',
       name: '_placeHolderMsg',
       desc: 'Placeholder text for a date range picker with an empty range.');
 }

lib/material_datepicker/material_datepicker.dart

@@ -215,7 +215,7 @@ class MaterialDatepickerComponent extends KeyboardHandlerMixin
       desc: 'Placeholder text for an empty date picker text box.');
 
   /// Gets the i18n'ed "Custom" label text.
-  String get customDateMsg => Intl.message('Custom',
+  static final customDateMsg = Intl.message('Custom',
       name: 'customDateMsg',
       desc: 'Indicates that a single custom date is selected');
 

lib/material_datepicker/material_time_picker.dart

@@ -322,11 +322,11 @@ class MaterialTimePickerComponent extends KeyboardHandlerMixin
     event.stopPropagation();
   }
 
-  String get dropdownPlaceholderMsg => Intl.message('Select time',
+  static final dropdownPlaceholderMsg = Intl.message('Select time',
       name: 'MaterialTimePickerComponent_dropdownPlaceholderMsg',
       desc: 'Placeholder text for an empty time picker dropdown button.');
 
-  String get inputPlaceholderMsg => Intl.message('Enter time',
+  static final inputPlaceholderMsg = Intl.message('Enter time',
       name: 'MaterialTimePickerComponent_inputPlaceholderMsg',
       desc: 'Placeholder text for an empty time picker input box.');
 

lib/material_datepicker/next_prev_buttons.dart

@@ -110,12 +110,12 @@ class NextPrevComponent implements OnDestroy {
   /// Whether the next button is disabled.
   bool get isNextDisabled => disabled || !hasNext;
 
-  static String get _genericNextMsg => Intl.message('Next',
+  static final _genericNextMsg = Intl.message('Next',
       name: '_genericNextMsg',
       meaning: 'For a button which moves to the next item',
       desc: 'Label for a button to move to the next item of some series.');
 
-  static String get _genericPrevMsg => Intl.message('Previous',
+  static final _genericPrevMsg = Intl.message('Previous',
       name: '_genericPrevMsg',
       meaning: 'For a button which moves to the previous item',
       desc: 'Label for a button to move to the previous item of some series.');

lib/material_datepicker/range.dart

@@ -900,7 +900,7 @@ List<DatepickerDateRange> commonRanges(Clock clock) => [
       allTime,
     ];
 
-String get _customDateRangeMsg => Intl.message('Custom',
+final _customDateRangeMsg = Intl.message('Custom',
     name: '_customDateRangeMsg',
     meaning: 'Name of a date range',
     desc: 'Name of a user-specified date range, as opposed to a predefined '

lib/src/material_datepicker/comparison_range_editor.dart

@@ -48,7 +48,7 @@ class ComparisonRangeEditorComponent {
     ComparisonOption.custom
   ];
 
-  String get comparisonHeaderMsg => Intl.message('Compare',
+  static final comparisonHeaderMsg = Intl.message('Compare',
       name: 'comparisonHeaderMsg',
       desc: 'Label for a toggle that turns time comparison on/off.');
 
@@ -59,20 +59,20 @@ class ComparisonRangeEditorComponent {
     return prev?.isPredefined == true ? prev.title : _previousPeriodMsg;
   }
 
-  String get _previousPeriodMsg => Intl.message('Previous period',
+  static final _previousPeriodMsg = Intl.message('Previous period',
       name: '_previousPeriodMsg',
       meaning: 'Name for a time comparison option',
       desc: 'Setting to compare the selected date range with the previous '
           'period. E.g. if the selected range were May, this would be April.');
 
-  String get samePeriodLastYearMsg => Intl.message('Previous year',
+  static final samePeriodLastYearMsg = Intl.message('Previous year',
       name: 'samePeriodLastYearMsg',
       meaning: 'Name for a time comparison option',
       desc: 'Setting to compare the selected date range with the same range '
           'last year. E.g. if the selected range were May 2015, this would be '
           'May 2014.');
 
-  String get customMsg => Intl.message('Custom',
+  static final customMsg = Intl.message('Custom',
       name: 'customMsg',
       meaning: 'Name for a time comparison option',
       desc: 'Setting to compare the selected date range with another arbitrary '