Mac: Use 512x512 tiles by default when on high DPI devices

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 160 matching lines @@
       default_tile_size += 32;
   } else {
     // We don't know the exact resolution due to screen controls etc.
     // So this just estimates the values above using tile counts.
     int numTiles = (display_width * display_height) / (256 * 256);
     if (numTiles > 16)
       default_tile_size = 384;
     if (numTiles >= 40)
       default_tile_size = 512;
   }
-#elif defined(OS_CHROMEOS)
+#elif defined(OS_CHROMEOS) || defined(OS_MACOSX)
   // Use 512 for high DPI (dsf=2.0f) devices.
   if (initial_device_scale_factor >= 2.0f)
     default_tile_size = 512;
 #endif
 
   return gfx::Size(default_tile_size, default_tile_size);
 }
 
 // Check cc::TopControlsState, and blink::WebTopControlsState
 // are kept in sync.
@@ skipping 943 matching lines @@
 #endif
   return actual;
 }
 
 void RenderWidgetCompositor::SetPaintedDeviceScaleFactor(
     float device_scale) {
   layer_tree_host_->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 }  // namespace content