[Clean] Add unittest target and BrowserCoordinator tests.

ios/clean/chrome/browser/BUILD.gn

 # Copyright 2015 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("browser") {
   sources = [
     "browser_coordinator+internal.h",
     "browser_coordinator.h",
     "browser_coordinator.mm",
     "url_opening.h",
   ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
 
   deps = [
     "//base",
+    "//ios/chrome/app:tests_fake_hook",

[marq (ping after 24h), 2017/01/11 13:13:25]

These additions are required to link ChromeBrowserState :-(.

     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",
+    "//ios/chrome/browser/tabs:tabs_internal",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "browser_coordinator_unittest.mm",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  deps = [
+    ":browser",
+    "//base",
+    "//base/test:test_support",
+    "//ios/chrome/test/base",
+    "//testing/gtest",
+  ]
+}