Split //ios/public/provider/chrome/browser/* targets.

ios/public/provider/chrome/browser/distribution/BUILD.gn

Index: ios/public/provider/chrome/browser/distribution/BUILD.gn
diff --git a/ios/public/provider/chrome/browser/distribution/BUILD.gn b/ios/public/provider/chrome/browser/distribution/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..ee5a48b313d2c41b412de67faad2c9605e96848b
--- /dev/null
+++ b/ios/public/provider/chrome/browser/distribution/BUILD.gn
@@ -0,0 +1,25 @@
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+source_set("distribution") {
+  sources = [
+    "app_distribution_provider.h",
+    "app_distribution_provider.mm",
+  ]
+  deps = [
+    "//base",
+  ]
+}
+
+source_set("test_support") {
+  testonly = true
+  sources = [
+    "test_app_distribution_provider.h",
+    "test_app_distribution_provider.mm",
+  ]
+  deps = [
+    "//base",
+    "//ios/public/provider/chrome/browser/distribution",
+  ]
+}