[BottomSheet] Add an app bar to the typical use example. (#4268)

Closes https://github.com/material-components/material-components-ios/issues/4236

![example](https://user-images.githubusercontent.com/45670/40505345-ebb13a00-5f61-11e8-89d7-c51d9e45150a.gif)

components/BottomSheet/examples/BottomSheetTypicalUseExample.m

@@ -16,6 +16,9 @@
 
 #import <UIKit/UIKit.h>
 
+#import "MaterialAppBar.h"
+#import "MaterialAppBar+ColorThemer.h"
+#import "MaterialAppBar+TypographyThemer.h"
 #import "MaterialBottomSheet.h"
 #import "supplemental/BottomSheetDummyCollectionViewController.h"
 #import "supplemental/BottomSheetSupplemental.h"
@@ -25,10 +28,19 @@ @implementation BottomSheetTypicalUseExample
 - (void)presentBottomSheet {
   BottomSheetDummyCollectionViewController *viewController =
       [[BottomSheetDummyCollectionViewController alloc] initWithNumItems:102];
-  viewController.preferredContentSize = CGSizeMake(500, 200);
+  viewController.title = @"Bottom sheet example";
+
+  MDCAppBarContainerViewController *container =
+      [[MDCAppBarContainerViewController alloc] initWithContentViewController:viewController];
+  container.preferredContentSize = CGSizeMake(500, 200);
+  container.appBar.headerViewController.headerView.trackingScrollView =
+      viewController.collectionView;
+
+  [MDCAppBarColorThemer applySemanticColorScheme:self.colorScheme toAppBar:container.appBar];
+  [MDCAppBarTypographyThemer applyTypographyScheme:self.typographyScheme toAppBar:container.appBar];
 
   MDCBottomSheetController *bottomSheet =
-      [[MDCBottomSheetController alloc] initWithContentViewController:viewController];
+      [[MDCBottomSheetController alloc] initWithContentViewController:container];
   bottomSheet.trackingScrollView = viewController.collectionView;
   [self presentViewController:bottomSheet animated:YES completion:nil];
 }

components/BottomSheet/examples/supplemental/BottomSheetPresenterViewController.h

@@ -16,8 +16,14 @@
 
 #import <UIKit/UIKit.h>
 
+#import "MaterialColorScheme.h"
+#import "MaterialTypographyScheme.h"
+
 @interface BottomSheetPresenterViewController : UIViewController
 
+@property(nonatomic, strong) MDCSemanticColorScheme *colorScheme;
+@property(nonatomic, strong) MDCTypographyScheme *typographyScheme;
+
 - (void)presentBottomSheet;
 
 @end

components/BottomSheet/examples/supplemental/BottomSheetPresenterViewController.m

@@ -22,6 +22,15 @@ @implementation BottomSheetPresenterViewController {
   MDCButton *_button;
 }
 
+- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
+  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
+  if (self) {
+    _colorScheme = [[MDCSemanticColorScheme alloc] init];
+    _typographyScheme = [[MDCTypographyScheme alloc] init];
+  }
+  return self;
+}
+
 - (void)viewDidLoad {
   [super viewDidLoad];