cc: Refactor SkipImageCanvas and create it during playback.

This patch moves SkipImageCanvas into a separate file in the same
directory as ImageHijackCanvas and also moves the creation of
SkipImageCanvas to raster source playback (the same place as
ImageHijackCanvas is created).

BUG=594679
R=enne, ericrk
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1799883002

Cr-Commit-Position: refs/heads/master@{#381101}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 38006a7..f5eacc1 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -309,6 +309,8 @@
     "playback/image_hijack_canvas.h",
     "playback/largest_display_item.cc",
     "playback/largest_display_item.h",
+    "playback/skip_image_canvas.cc",
+    "playback/skip_image_canvas.h",
     "playback/transform_display_item.cc",
     "playback/transform_display_item.h",
     "proto/base_conversions.cc",