[arc-intents] Properly qualify API-generated page transitions.

Unqualified page transitions are treated as link-clicks, which can get
sent to android via the arc intent mechanism.  This can result in
infinite-looping if the URL that is being opened originated from android
in the first place.

Marking this as an API-generated page transition ensures that the arc
intent code does not forward this URL back to android.

BUG=632360

Review-Url: https://codereview.chromium.org/2189063002
Cr-Commit-Position: refs/heads/master@{#408775}
diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index 3bbc53e..e815146 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -204,7 +204,7 @@
   return new TestKeyboardUI;
 }
 
-void ShellDelegateImpl::OpenUrl(const GURL& url) {}
+void ShellDelegateImpl::OpenUrlFromArc(const GURL& url) {}
 
 app_list::AppListPresenter* ShellDelegateImpl::GetAppListPresenter() {
   if (!app_list_presenter_) {