[ios] Dispatcher for tab_strip and tab_grid.

ios/clean/chrome/browser/ui/tab_collection/tab_collection_view_controller.mm

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_view_controller.h"
 
 #include "base/mac/foundation_util.h"
-#import "ios/clean/chrome/browser/ui/commands/tab_commands.h"
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_data_source.h"
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_tab_cell.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 @interface TabCollectionViewController ()<UICollectionViewDataSource,
                                           UICollectionViewDelegate,
                                           SessionCellDelegate>
 @property(nonatomic, readwrite) UICollectionView* tabs;
 @end
 
 @implementation TabCollectionViewController
 @synthesize tabs = _tabs;
 @synthesize dataSource = _dataSource;
-@synthesize tabCommandHandler = _tabCommandHandler;
 
 #pragma mark - UIViewController
 
 - (void)viewDidLoad {
   [super viewDidLoad];
   UICollectionView* tabs =
       [[UICollectionView alloc] initWithFrame:CGRectZero
                          collectionViewLayout:[self collectionViewLayout]];
   tabs.translatesAutoresizingMaskIntoConstraints = NO;
   tabs.backgroundColor = [UIColor blackColor];
@@ skipping 19 matching lines @@
 
 #pragma mark - Required subclass override
 
 - (UICollectionViewLayout*)collectionViewLayout {
   [NSException
        raise:NSInternalInconsistencyException
       format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
   return nil;
 }
 
+- (void)showTabAtIndex:(int)index {
+  [NSException

[marq (ping after 24h), 2017/03/30 08:46:18]

We prefer not to raise ObjC exceptions (see
https://google.github.io/styleguide/objcguide.xml?showone=Avoid_Throwing_Exce...).
This is where NOTREACHED() should be used (from base/logging.h):

NOTREACHED() << "You must override " <<
base::SysNSStringToUTF8(NSStringFromSelector(_cmd)) << " in a subclass."

(you will need base/strings/sys_string_conversions.h as well).

[edchin, 2017/03/30 18:15:51]

Done.

+       raise:NSInternalInconsistencyException
+      format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
+}
+
+- (void)closeTabAtIndex:(int)index {
+  [NSException
+       raise:NSInternalInconsistencyException
+      format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
+}
+
 #pragma mark - UICollectionViewDataSource methods
 
 - (NSInteger)numberOfSectionsInCollectionView:
     (UICollectionView*)collectionView {
   return 1;
 }
 
 - (NSInteger)collectionView:(UICollectionView*)collectionView
      numberOfItemsInSection:(NSInteger)section {
   return [self.dataSource numberOfTabs];
@@ skipping 29 matching lines @@
 
 - (TabSwitcherCache*)tabSwitcherCache {
   // PLACEHOLDER: return image cache.
   return nil;
 }
 
 - (void)cellPressed:(UICollectionViewCell*)cell {
   NSInteger item = [[self.tabs indexPathForCell:cell] item];
   DCHECK_LE(item, INT_MAX);
   int index = static_cast<int>(item);
-  [self.tabCommandHandler showTabAtIndex:index];
+  [self showTabAtIndex:index];
 }
 
 - (void)deleteButtonPressedForCell:(UICollectionViewCell*)cell {
   NSInteger item = [[self.tabs indexPathForCell:cell] item];
   DCHECK_LE(item, INT_MAX);
   int index = static_cast<int>(item);
-  [self.tabCommandHandler closeTabAtIndex:index];
+  [self closeTabAtIndex:index];
 }
 
 #pragma mark - TabCollectionConsumer methods
 
 - (void)insertItemAtIndex:(int)index {
   [self.tabs insertItemsAtIndexPaths:@[ [NSIndexPath indexPathForItem:index
                                                             inSection:0] ]];
 }
 
 - (void)deleteItemAtIndex:(int)index {
   [self.tabs deleteItemsAtIndexPaths:@[ [NSIndexPath indexPathForItem:index
                                                             inSection:0] ]];
 }
 
 - (void)reloadItemsAtIndexes:(NSIndexSet*)indexes {
   NSMutableArray<NSIndexPath*>* indexPaths = [[NSMutableArray alloc] init];
   [indexes enumerateIndexesUsingBlock:^(NSUInteger index, BOOL* _Nonnull stop) {
     [indexPaths addObject:[NSIndexPath indexPathForItem:index inSection:0]];
   }];
   [self.tabs reloadItemsAtIndexPaths:indexPaths];
 }
 
 @end