[ash-md] Improves smoothness with many windows in overview

ash/common/ash_switches.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/ash_switches.h"
 
 #include "base/command_line.h"
 #include "base/sys_info.h"
 
 namespace ash {
@@ skipping 80 matching lines @@
 // "800,0+800-800x800,0+1600-800x800" for three displays at 800x800 resolution.
 const char kAshHostWindowBounds[] = "ash-host-window-bounds";
 
 // Specifies if Material Design elements in Chrome OS system UI are enabled.
 // Can be disabled / enabled / experimental allowing to launch incrementally.
 const char kAshMaterialDesign[] = "ash-md";
 const char kAshMaterialDesignDisabled[] = "disabled";
 const char kAshMaterialDesignEnabled[] = "enabled";
 const char kAshMaterialDesignExperimental[] = "experimental";
 
+// Specifies a maximum number of preview windows in overview mode that still
+// allows using mask layers to hide the original window header and use rounded
+// corners.
+const char kAshMaxWindowsToUseMaskInOverview[] = "ash-max-previews-to-use-mask";
+
+// Specifies a maximum number of preview windows in overview mode that still
+// allows using alpha shapes to hide the original window header.
+const char kAshMaxWindowsToUseShapeInOverview[] =
+    "ash-max-previews-to-use-shape";
+
 // Specifies the layout mode and offsets for the secondary display for
 // testing. The format is "<t|r|b|l>,<offset>" where t=TOP, r=RIGHT,
 // b=BOTTOM and L=LEFT. For example, 'r,-100' means the secondary display
 // is positioned on the right with -100 offset. (above than primary)
 const char kAshSecondaryDisplayLayout[] = "ash-secondary-display-layout";
 
 // Enables the heads-up display for tracking touch points.
 const char kAshTouchHud[] = "ash-touch-hud";
 
 // Uses the 1st display in --ash-host-window-bounds as internal display.
@@ skipping 21 matching lines @@
 
   return base::SysInfo::IsRunningOnChromeOS() ||
          base::CommandLine::ForCurrentProcess()->HasSwitch(
              kAshConstrainPointerToRoot);
 }
 
 #endif
 
 }  // namespace switches
 }  // namespace ash