[ios] Creates showSnackbarWithMessage command

This new commands shows a Snackbar by creating the MDCSnackBarCommand in
the Coordinator, thus saving the caller to import Material components.

Bug: 1085419
Change-Id: Iee3d6c93f40b50558503d997d13c540d9e84c86d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333069
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795003}

ios/chrome/browser/ui/commands/snackbar_commands.h

@@ -21,6 +21,17 @@
 - (void)showSnackbarMessage:(MDCSnackbarMessage*)message
                bottomOffset:(CGFloat)offset;
 
+// Shows a snackbar displaying a message with |messageText| and a button with
+// |buttonText| which triggers |messageAction| on tap. |completionAction| will
+// be called when the snackbar finishes presenting, BOOL is YES if the dismissal
+// was caused by a user action and NO if not. It will use the Bottom toolbar
+// height as bottom offset. Use this method if displaying a Snackbar while the
+// Web content is visible. If there's no bottom toolbar offset will be 0.
+- (void)showSnackbarWithMessage:(NSString*)messageText
+                     buttonText:(NSString*)buttonText
+                  messageAction:(void (^)(void))messageAction
+               completionAction:(void (^)(BOOL))completionAction;
+
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_COMMANDS_SNACKBAR_COMMANDS_H_

ios/chrome/browser/ui/snackbar/snackbar_coordinator.mm

@@ -49,4 +49,25 @@
   [[MDCSnackbarManager defaultManager] showMessage:message];
 }
 
+- (void)showSnackbarWithMessage:(NSString*)messageText
+                     buttonText:(NSString*)buttonText
+                  messageAction:(void (^)(void))messageAction
+               completionAction:(void (^)(BOOL))completionAction {
+  MDCSnackbarMessageAction* action = [[MDCSnackbarMessageAction alloc] init];
+  action.handler = messageAction;
+  action.title = buttonText;
+  action.accessibilityLabel = buttonText;
+  MDCSnackbarMessage* message =
+      [MDCSnackbarMessage messageWithText:messageText];
+  message.action = action;
+  message.completionHandler = completionAction;
+
+  NamedGuide* bottomToolbarGuide =
+      [NamedGuide guideWithName:kSecondaryToolbarGuide
+                           view:self.baseViewController.view];
+  CGRect bottomToolbarFrame = bottomToolbarGuide.constrainedView.frame;
+  [self showSnackbarMessage:message
+               bottomOffset:bottomToolbarFrame.size.height];
+}
+
 @end