Move session into //blimp/client/app and update GN files.

blimp/client/core/geolocation/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("geolocation") {
   visibility = [
+    "//blimp/client/app:session",  # TODO(nyquist): Remove this. See crbug/651964.
     "//blimp/client/core/*",
-    "//blimp/client:session",
     "//blimp/engine:browser_tests",
   ]
 
   sources = [
     "geolocation_feature.cc",
     "geolocation_feature.h",
   ]
 
   deps = [
     "//base:base",
@@ skipping 30 matching lines @@
     "//blimp/test:support",
     "//cc/proto",
     "//device/geolocation",
     "//device/geolocation:test_support",
     "//net",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }