[Panel refactor] use browserless Panels by default in Dev/Canary

chrome/browser/ui/panels/panel_manager.h

Index: chrome/browser/ui/panels/panel_manager.h
diff --git a/chrome/browser/ui/panels/panel_manager.h b/chrome/browser/ui/panels/panel_manager.h
index 15df470b07c5a11361b0ed73d4e0feddbdc2d434..45067c4d526ca5d6db51d281cf2cb75748f424ec 100644
--- a/chrome/browser/ui/panels/panel_manager.h
+++ b/chrome/browser/ui/panels/panel_manager.h
@@ -34,6 +34,10 @@ class PanelManager : public DisplaySettingsProvider::DisplayAreaObserver,
   // Returns true if panels should be used for the extension.
   static bool ShouldUsePanels(const std::string& extension_id);
 
+  // Returns true if using browserless panels. False if using old panels.
+  // TODO(jennb): Delete after refactor.
+  static bool UseBrowserlessPanels();
+
   // Creates a panel and returns it. The panel might be queued for display
   // later.
   // |app_name| is the default title for Panels when the page content does not