[Payment Request] Populates region field if region code/name is valid.

ios/chrome/browser/ui/payments/address_edit_mediator.mm

Index: ios/chrome/browser/ui/payments/address_edit_mediator.mm
diff --git a/ios/chrome/browser/ui/payments/address_edit_mediator.mm b/ios/chrome/browser/ui/payments/address_edit_mediator.mm
index 568608fb8338ecb9c4b46d5c49626704c24134e4..19a2834e4a32e8cc85f4f058409c3fe70d4a16d5 100644
--- a/ios/chrome/browser/ui/payments/address_edit_mediator.mm
+++ b/ios/chrome/browser/ui/payments/address_edit_mediator.mm
@@ -10,6 +10,7 @@
 #include <utility>
 
 #include "base/callback.h"
+#include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/values.h"
@@ -68,7 +69,6 @@
 @synthesize consumer = _consumer;
 @synthesize countries = _countries;
 @synthesize selectedCountryCode = _selectedCountryCode;
-@synthesize regions = _regions;
 @synthesize paymentRequest = _paymentRequest;
 @synthesize address = _address;
 @synthesize fieldsMap = _fieldsMap;
@@ -126,28 +126,32 @@
 #pragma mark - RegionDataLoaderConsumer
 
 - (void)regionDataLoaderDidSucceedWithRegions:
-    (NSMutableArray<NSString*>*)regions {
-  self.regions = regions;
+    (NSDictionary<NSString*, NSString*>*)regions {
   // Enable the previously disabled field.
   self.regionField.enabled = YES;
 
-  // If an address is being edited and it has a valid region, the field value is
-  // set to that region. Otherwise, set the field value to nil. If creating an
-  // address, set the first available region as the field value, if possible.
+  // An autofill profile may have a region code or a region name stored as the
+  // autofill::ADDRESS_HOME_STATE. If an address is being edited whose value for
+  // that field type is a valid region code or a valid region name, the editor
+  // field value is set to the respective region code. Otherwise, it is set to
+  // nil.
+  self.regionField.value = nil;
   if (self.address) {
     NSString* region =
         [self fieldValueFromProfile:self.address
                           fieldType:autofill::ADDRESS_HOME_STATE];
-    self.regionField.value =
-        [self.regions containsObject:region] ? region : nil;
-  } else {
-    self.regionField.value = regions.count ? regions[0] : nil;
+    if ([regions objectForKey:region]) {
+      self.regionField.value = region;
+    } else if ([[regions allKeysForObject:region] count]) {
+      DCHECK(1 == [[regions allKeysForObject:region] count]);
+      self.regionField.value = [regions allKeysForObject:region][0];
+    }
   }
 
   // Notify the view controller asynchronously to allow for the view to update.
   __weak AddressEditMediator* weakSelf = self;
   dispatch_async(dispatch_get_main_queue(), ^{
-    [weakSelf.consumer setOptions:weakSelf.regions
+    [weakSelf.consumer setOptions:[regions allKeys]
                    forEditorField:weakSelf.regionField];
   });
 }