Add the suggestions UI in chrome

ios/chrome/browser/content_suggestions/content_suggestions_coordinator.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/chrome/browser/content_suggestions/content_suggestions_coordinator.h"
+
+#include "base/mac/scoped_nsobject.h"
+#import "ios/chrome/browser/ui/suggestions/suggestions_commands.h"
+#import "ios/chrome/browser/ui/suggestions/suggestions_view_controller.h"
+#include "ios/chrome/grit/ios_strings.h"
+#include "ui/base/l10n/l10n_util.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface ContentSuggestionsCoordinator ()<SuggestionsCommands> {
+  UINavigationController* _navigationController;
+}
+
+@end
+
+@implementation ContentSuggestionsCoordinator
+
+@synthesize visible = _visible;
+
+- (void)start {
+  if (self.visible) {
+    // Prevent this coordinator to be started twice in a row.

[marq (ping after 24h), 2017/01/24 10:09:22]

nit: "to be started" --> "from being started"

[gambard, 2017/01/25 08:09:50]

Done.

+    return;
+  }
+
+  _visible = YES;
+
+  SuggestionsViewController* suggestionsViewController =
+      [[SuggestionsViewController alloc]
+          initWithStyle:CollectionViewControllerStyleDefault];
+
+  suggestionsViewController.suggestionCommandHandler = self;
+  _navigationController = [[UINavigationController alloc]
+      initWithRootViewController:suggestionsViewController];
+
+  suggestionsViewController.navigationItem.leftBarButtonItem =
+      [[UIBarButtonItem alloc]
+          initWithTitle:l10n_util::GetNSString(IDS_IOS_SUGGESTIONS_DONE)
+                  style:UIBarButtonItemStylePlain
+                 target:self
+                 action:@selector(stop)];
+
+  [self.baseViewController presentViewController:_navigationController
+                                        animated:YES
+                                      completion:nil];
+}
+
+- (void)stop {
+  [[_navigationController presentingViewController]
+      dismissViewControllerAnimated:YES
+                         completion:nil];
+  _navigationController = nil;
+  _visible = NO;
+}
+
+#pragma mark - SuggestionsCommands
+
+- (void)openReadingList {
+}
+
+- (void)openFirstPageOfReadingList {
+}
+
+- (void)addEmptyItem {
+}
+
+- (void)openFaviconAtIndex:(NSInteger)index {
+}
+
+@end