Add support for building "ios_chrome_unittests" with gn.

ios/chrome/common/BUILD.gn

Index: ios/chrome/common/BUILD.gn
diff --git a/cloud_print/common/BUILD.gn b/ios/chrome/common/BUILD.gn
similarity index 50%
copy from cloud_print/common/BUILD.gn
copy to ios/chrome/common/BUILD.gn
index ca0b546d10481b4239afbd3eb292adb74f8490f4..67db8c073168e08cdff35e608ad3f5369d20cd93 100644
--- a/cloud_print/common/BUILD.gn
+++ b/ios/chrome/common/BUILD.gn
@@ -4,23 +4,20 @@
 
 source_set("common") {
   sources = [
-    "win/cloud_print_utils.cc",
-    "win/cloud_print_utils.h",
+    "channel_info.h",
+    "channel_info.mm",
+    "string_util.h",
+    "string_util.mm",
   ]
 
   deps = [
     "//base",
-  ]
-}
-
-source_set("install_utils") {
-  sources = [
-    "win/install_utils.cc",
-    "win/install_utils.h",
+    "//components/version_info",
+    "//ios/chrome/common/app_group:main_app",
   ]
 
-  deps = [
-    ":common",
-    "//base",
+  libs = [
+    "CoreGraphics.framework",
+    "Foundation.framework",
   ]
 }