Cleanup blimp/client/core code organization.

blimp/client/core/session/BUILD.gn

 # 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.
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
 
 source_set("session") {
@@ skipping 20 matching lines @@
     "//base",
     "//blimp/client/public:public_headers",
     "//blimp/net",
     "//components/safe_json",
     "//google_apis",
     "//net",
     "//url",
   ]
 
   deps = [
-    "//blimp/client/core:switches",
+    "//blimp/client/core/switches",
     "//blimp/common",
   ]
 }
 
 source_set("unit_tests") {
   visibility = [ "//blimp/client/core:unit_tests" ]
 
   testonly = true
 
   sources = [
@@ skipping 10 matching lines @@
   ]
 
   data = []
 
   # TODO(dtrainor): Fix the test harness to allow this to run on Android.
   # See crbug.com/588240.
   if (is_linux) {
     sources += [ "assignment_source_unittest.cc" ]
 
     deps += [
-      "//blimp/client/core:switches",
+      "//blimp/client/core/switches",
       "//blimp/common",
       "//blimp/common:test_support",
       "//components/safe_json:test_support",
       "//net:test_support",
       "//url",
     ]
 
     data += [
       "test_selfsigned_cert.pem",
       "//blimp/test/data/test_client_token",
     ]
   }
 }