Add ContentSuggestionsMediator

ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm

Index: ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm
diff --git a/ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm b/ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm
index 0df1af28a4f22c989c334b1f7d501acc80fb752e..add8b361a455ec12127a6cc9bc3f992615e3f6f1 100644
--- a/ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm
+++ b/ios/chrome/browser/content_suggestions/content_suggestions_coordinator.mm
@@ -5,6 +5,8 @@
 #import "ios/chrome/browser/content_suggestions/content_suggestions_coordinator.h"
 
 #include "base/mac/scoped_nsobject.h"
+#import "ios/chrome/browser/content_suggestions/content_suggestions_mediator.h"
+#include "ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_commands.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.h"
 #include "ios/chrome/grit/ios_strings.h"
@@ -22,19 +24,27 @@
 
 @implementation ContentSuggestionsCoordinator
 
+@synthesize browserState = _browserState;
 @synthesize visible = _visible;
 
 - (void)start {
-  if (self.visible) {
-    // Prevent this coordinator from being started twice in a row.
+  if (self.visible || !self.browserState) {
+    // Prevent this coordinator from being started twice in a row or without a
+    // browser state.
     return;
   }
 
   _visible = YES;
 
+  ContentSuggestionsMediator* contentSuggestionsMediator =
+      [[ContentSuggestionsMediator alloc]
+          initWithContentService:IOSChromeContentSuggestionsServiceFactory::

[lpromero, 2017/01/26 10:10:20]

Should you just pass the ContentService to this coordinator?
Mark, what is your global vision on this? New Arch coordinators all have a
browserState, does that mean that the coordinators are also responsible to
create the right service they need?
I don't yet see any issue with both approaches. Just trying to sync with the big
picture.

[marq (ping after 24h), 2017/01/27 12:44:55]

Globally the idea was that coordinators would manipulate browserStates and pass
specific services into non-coordinator objects. The general idea is to keep the
public API of coordinators simple enough so we don't need to pass specific
services up and down the chain.

[gambard, 2017/01/30 15:19:17]

Acknowledged.
I keep the browserState.

+                                     GetForBrowserState(self.browserState)];
+
   ContentSuggestionsViewController* suggestionsViewController =
       [[ContentSuggestionsViewController alloc]
-          initWithStyle:CollectionViewControllerStyleDefault];
+          initWithStyle:CollectionViewControllerStyleDefault
+             dataSource:contentSuggestionsMediator];
 
   suggestionsViewController.suggestionCommandHandler = self;
   _navigationController = [[UINavigationController alloc]