Adding experimental maximize mode (behind a flag)

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 892b04aa2b90cceb007e9a99047831c9cb46ed5f..974947ac383fcd333b58463ef97e561e3e3c9565 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -199,6 +199,10 @@ class ASH_EXPORT Shell
   // True if "launcher per display" feature  is enabled.
   static bool IsLauncherPerDisplayEnabled();
 
+  // True if an experimental maximize mode is enabled which forces browser and
+  // application windows to be maximized.
+  static bool IsForcedMaximizeMode();
+
   void set_active_root_window(aura::RootWindow* active_root_window) {
     active_root_window_ = active_root_window;
   }