Roll common to d7c2e2b9464.

Picks up code removal and changes to download_file.

https://skia.googlesource.com/common.git/+log/5eee100ab..d7c2e2b9464

Review URL: https://codereview.chromium.org/700763003
diff --git a/DEPS b/DEPS
index 7a0422b..34a86ac 100644
--- a/DEPS
+++ b/DEPS
@@ -3,7 +3,7 @@
 # Dependencies on outside packages.
 #
 deps = {
-  "common": "https://skia.googlesource.com/common.git@5eee100abacd0c2fc89121418627cf55ca2eda31",
+  "common": "https://skia.googlesource.com/common.git@d7c2e2b9464e70e0f3847a330b930d008dc8c8db",
 
   "third_party/externals/angle2" : "https://chromium.googlesource.com/angle/angle.git@23a8a433529d9db23882c702a29d5e594841563d",
   "third_party/externals/freetype" : "https://skia.googlesource.com/third_party/freetype2.git@VER-2-5-0-1",