[Handoff] Modify activityType to allow Handoff to native apps

NSUserActivityTypeBrowsingWeb indicates to the system that the user is browsing a website. This allows iOS to suggest native apps that have claimed the domain in their associated domains rather than always suggesting Safari.

Change-Id: Ia08abb20f258f8dad474c081cfd59ff0d1666a9f
Reviewed-on: https://chromium-review.googlesource.com/c/1270882Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Sawyer Vaughan <sawyervaughan@google.com>
Cr-Commit-Position: refs/heads/master@{#599265}

components/handoff/handoff_manager.mm

@@ -99,7 +99,7 @@
   [self.userActivity invalidate];
 
   base::scoped_nsobject<NSUserActivity> userActivity([[NSUserActivity alloc]
-      initWithActivityType:handoff::kChromeHandoffActivityType]);
+      initWithActivityType:NSUserActivityTypeBrowsingWeb]);
   self.userActivity = userActivity;
   self.userActivity.webpageURL = net::NSURLWithGURL(_activeURL);
   NSString* origin = handoff::StringFromOrigin(_origin);