Portals: Add synthetic trial for portals.

Bug: 1045567
Change-Id: Ie8e18e211552a3b1a7259a689136e8fd2e1e8732
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028295Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Lucas Gadani <lfg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738012}

chrome/browser/metrics/chrome_metrics_service_accessor.h

@@ -113,6 +113,7 @@ class ChromeMetricsServiceAccessor : public metrics::MetricsServiceAccessor {
   friend void welcome::JoinOnboardingGroup(Profile* profile);
   friend class NavigationMetricsRecorder;
   friend class ChromeBrowserMainExtraPartsGpu;
+  friend class Browser;
 
   // Testing related friends.
   friend class first_run::FirstRunMasterPrefsVariationsSeedTest;

chrome/browser/ui/browser.cc

@@ -64,6 +64,7 @@
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/lifetime/browser_shutdown.h"
 #include "chrome/browser/media/webrtc/media_capture_devices_dispatcher.h"
+#include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/browser/permissions/permission_request_manager.h"
 #include "chrome/browser/picture_in_picture/picture_in_picture_window_manager.h"
@@ -1736,6 +1737,9 @@ void Browser::WebContentsCreated(WebContents* source_contents,
 }
 
 void Browser::PortalWebContentsCreated(WebContents* portal_web_contents) {
+  ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial("PortalsActive",
+                                                            "Enabled");
+
   TabHelpers::AttachTabHelpers(portal_web_contents);
 
   // Make the portal show up in the task manager.