Added CheckForFirstPartyApps() to ChromeBrowserProvider.

This is the first step of removing another use of Native App Whitelist
Manager. At this time, the Native App is only used for checking whether
certain Google native iOS apps are installed. This CL creates a new
null-implementation API in ChromeBrowserProvider for doing just that.

The next several steps will be
- implementing this API downstream
- switch upstream to use this new API
- remove GetNativeAppWhitelistManager() API

Bug: 742617
Change-Id: I6553a85743f1328ff8d6f5fca2a466af53d9a393
Reviewed-on: https://chromium-review.googlesource.com/571313
Commit-Queue: Peter Lee <pkl@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486873}

ios/public/provider/chrome/browser/chrome_browser_provider.h

@@ -157,6 +157,9 @@ class ChromeBrowserProvider {
   // Returns an instance of the spotlight provider.
   virtual SpotlightProvider* GetSpotlightProvider() const;
 
+  // Checks for native iOS apps that are installed.
+  virtual void CheckForFirstPartyApps() const;
+
   // Adds and removes observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);

ios/public/provider/chrome/browser/chrome_browser_provider.mm

@@ -108,6 +108,8 @@ SpotlightProvider* ChromeBrowserProvider::GetSpotlightProvider() const {
   return nullptr;
 }
 
+void ChromeBrowserProvider::CheckForFirstPartyApps() const {}
+
 BrandedImageProvider* ChromeBrowserProvider::GetBrandedImageProvider() const {
   return nullptr;
 }

ios/public/provider/chrome/browser/test_chrome_browser_provider.h

@@ -33,6 +33,7 @@ class TestChromeBrowserProvider : public ChromeBrowserProvider {
   OmahaServiceProvider* GetOmahaServiceProvider() const override;
   UserFeedbackProvider* GetUserFeedbackProvider() const override;
   SpotlightProvider* GetSpotlightProvider() const override;
+  void CheckForFirstPartyApps() const override;
   BrandedImageProvider* GetBrandedImageProvider() const override;
   id<NativeAppWhitelistManager> GetNativeAppWhitelistManager() const override;
 

ios/public/provider/chrome/browser/test_chrome_browser_provider.mm

@@ -90,6 +90,8 @@ SpotlightProvider* TestChromeBrowserProvider::GetSpotlightProvider() const {
   return spotlight_provider_.get();
 }
 
+void TestChromeBrowserProvider::CheckForFirstPartyApps() const {}
+
 BrandedImageProvider* TestChromeBrowserProvider::GetBrandedImageProvider()
     const {
   return branded_image_provider_.get();