[iOS] Add AlertCoordinator initializer that takes a BrowserState.

This will allow AlertCoordinators to access FullscreenController, which
will provide the necessary insets to use for non-modal alert
presentation.

This CL also removes the unnecessary empty initializers, as this is
handled by the NS_UNAVAILABLE annotation now.

Bug: 674649
Change-Id: I0d1b5efbcf0266103090e879b078cef64df42593
Reviewed-on: https://chromium-review.googlesource.com/c/1340602
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613327}

ios/chrome/browser/ui/alert_coordinator/action_sheet_coordinator.h

@@ -28,6 +28,12 @@
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
                                      title:(NSString*)title
                                    message:(NSString*)message NS_UNAVAILABLE;
+- (instancetype)initWithBaseViewController:(UIViewController*)viewController
+                                     title:(NSString*)title
+                                   message:(NSString*)message
+                              browserState:
+                                  (ios::ChromeBrowserState*)browserState
+    NS_UNAVAILABLE;
 
 // Configures the underlying UIAlertController's popover arrow direction.
 // Default is UIPopoverArrowDirectionAny.

ios/chrome/browser/ui/alert_coordinator/action_sheet_coordinator.mm

@@ -38,13 +38,6 @@ enum class AnchorMode {
 @implementation ActionSheetCoordinator
 @synthesize popoverArrowDirection = _popoverArrowDirection;
 
-- (instancetype)initWithBaseViewController:(UIViewController*)viewController
-                                     title:(NSString*)title
-                                   message:(NSString*)message {
-  NOTREACHED();
-  return nil;
-}
-
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
                                      title:(NSString*)title
                                    message:(NSString*)message

ios/chrome/browser/ui/alert_coordinator/alert_coordinator.h

@@ -38,6 +38,12 @@
                                      title:(NSString*)title
                                    message:(NSString*)message
     NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithBaseViewController:(UIViewController*)viewController
+                                     title:(NSString*)title
+                                   message:(NSString*)message
+                              browserState:
+                                  (ios::ChromeBrowserState*)browserState
+    NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
     NS_UNAVAILABLE;

ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm

@@ -44,22 +44,34 @@
 @synthesize rawCancelAction = _rawCancelAction;
 @synthesize message = _message;
 
-- (instancetype)initWithBaseViewController:(UIViewController*)viewController {
-  NOTREACHED();
-  return nil;
-}
-
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
                                      title:(NSString*)title
                                    message:(NSString*)message {
   self = [super initWithBaseViewController:viewController browserState:nullptr];
   if (self) {
-    _title = [title copy];
-    _message = [message copy];
+    [self commonInitWithTitle:title message:message];
   }
   return self;
 }
 
+- (instancetype)initWithBaseViewController:(UIViewController*)viewController
+                                     title:(NSString*)title
+                                   message:(NSString*)message
+                              browserState:
+                                  (ios::ChromeBrowserState*)browserState {
+  self = [super initWithBaseViewController:viewController
+                              browserState:browserState];
+  if (self) {
+    [self commonInitWithTitle:title message:message];
+  }
+  return self;
+}
+
+- (void)commonInitWithTitle:(NSString*)title message:(NSString*)message {
+  _title = title;
+  _message = message;
+}
+
 #pragma mark - Public Methods.
 
 - (void)addItemWithTitle:(NSString*)title