Delete Mac & Cairo skia::BitmapPlatformDevice impls

skia/BUILD.gn

Index: skia/BUILD.gn
diff --git a/skia/BUILD.gn b/skia/BUILD.gn
index 64bc750cbd98b715a93e1704c1c0330d9eac7806..db9b5423096bd3791f073233590bde4e2626072d 100644
--- a/skia/BUILD.gn
+++ b/skia/BUILD.gn
@@ -367,10 +367,6 @@ component("skia") {
   # Select the right BitmapPlatformDevice.
   if (is_win) {
     sources += [ "ext/bitmap_platform_device_win.cc" ]
-  } else if (is_mac) {
-    sources += [ "ext/bitmap_platform_device_mac.cc" ]
-  } else if (use_cairo) {
-    sources += [ "ext/bitmap_platform_device_cairo.cc" ]
   } else if (!is_ios) {
     sources += [ "ext/bitmap_platform_device_skia.cc" ]
   }