add imgcvt

This uses skcms to convert an image into a PNG with a new color profile.

Change-Id: Iaefdbbfba6f4b85637386569a65355df255b980d
Reviewed-on: https://skia-review.googlesource.com/143709
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index f396cb9..517b76a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1561,6 +1561,15 @@
         ]
       }
     }
+    test_app("imgcvt") {
+      sources = [
+        "tools/imgcvt.cpp",
+      ]
+      deps = [
+        ":skcms",
+        ":skia",
+      ]
+    }
     test_app("dm") {
       sources = [
         "dm/DM.cpp",