Split //ios/chrome/browser in multiple targets.

ios/chrome/browser/sync/glue/BUILD.gn

Index: ios/chrome/browser/sync/glue/BUILD.gn
diff --git a/ios/public/consumer/base/BUILD.gn b/ios/chrome/browser/sync/glue/BUILD.gn
similarity index 52%
copy from ios/public/consumer/base/BUILD.gn
copy to ios/chrome/browser/sync/glue/BUILD.gn
index eb83ba22b1adcf0d9f15821bbf91574e002c623a..8fd8b306d47f3dacee16c9854ba291a4b69e67c4 100644
--- a/ios/public/consumer/base/BUILD.gn
+++ b/ios/chrome/browser/sync/glue/BUILD.gn
@@ -2,12 +2,16 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("base") {
+source_set("glue") {
   sources = [
-    "//ios/consumer/base/debugger.mm",
-    "//ios/public/consumer/base/debugger.h",
+    "sync_start_util.cc",
+    "sync_start_util.h",
   ]
   deps = [
     "//base",
+    "//components/browser_sync",
+    "//components/sync",
+    "//ios/chrome/browser/browser_state",
+    "//ios/web",
   ]
 }