Only support left/right maximizing at 50% width when the --ash-enable-alternate-caption-button

ash/accelerators/accelerator_controller.cc

Index: ash/accelerators/accelerator_controller.cc
diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index d80cfea83c1a2deec1c5d574b61f31fa543acb62..daa017c13bf62f368bf0a59040cd3e3d634f3c45 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -47,7 +47,6 @@
 #include "ash/wm/property_util.h"
 #include "ash/wm/window_cycle_controller.h"
 #include "ash/wm/window_util.h"
-#include "ash/wm/workspace/snap_sizer.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "content/public/browser/gpu_data_manager.h"
@@ -836,9 +835,11 @@ bool AcceleratorController::PerformAction(int action,
         break;
       }
 
-      internal::SnapSizer::SnapWindow(window,
-          action == WINDOW_SNAP_LEFT ? internal::SnapSizer::LEFT_EDGE :
-                                       internal::SnapSizer::RIGHT_EDGE);
+      if (wm::CanSnapWindow(window)) {
+        wm::SnapWindowToEdge(window,
+            action == WINDOW_SNAP_LEFT ? wm::SNAP_LEFT_EDGE :
+                                         wm::SNAP_RIGHT_EDGE);
+      }
       return true;
     }
     case WINDOW_MINIMIZE: {