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

blimp/client/core/settings/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("settings") {
-  visibility = [ "//blimp/client/*" ]
+  visibility = [
+    "//blimp/client/app:*",  # TODO(nyquist): Remove this. See crbug/651964.
+    "//blimp/client/core/*",
+  ]
 
   sources = [
     "blimp_settings_delegate.h",
     "settings_feature.cc",
     "settings_feature.h",
   ]
 
   deps = [
     "//blimp/common",
     "//net",
@@ skipping 13 matching lines @@
     deps += [
       ":settings_jni_headers",
       "//blimp/client/core/session",
       "//blimp/common",
     ]
   }
 }
 
 if (is_android) {
   android_library("settings_java") {
-    visibility = [ "//blimp/client/*" ]
+    visibility = [
+      "//blimp/client/app:*",  # TODO(nyquist): Remove this. See crbug/651964.
+      "//blimp/client/core/*",
+    ]
 
     java_files = [
       "android/java/src/org/chromium/blimp/core/settings/AboutBlimpPreferences.java",
       "android/java/src/org/chromium/blimp/core/settings/BlimpPreferencesDelegate.java",
     ]
 
     # TODO(xingliu): Clean resources files in the future. http://crbug.com/630687.
     deps = [
       "//base:base_java",
-      "//blimp/client:blimp_java_resources",
+      "//blimp/client/app:blimp_java_resources",
       "//blimp/client/core/common:common_java",
       "//blimp/client/public:public_headers_java",
       "//components/signin/core/browser/android:java",
       "//components/sync/android:sync_java",
       "//third_party/android_tools:android_support_v7_appcompat_java",
     ]
   }
 
   generate_jni("settings_jni_headers") {
     visibility = [ ":*" ]
 
     sources = [
       "android/java/src/org/chromium/blimp/core/settings/AboutBlimpPreferences.java",
     ]
 
     jni_package = "blimp/client/core/settings"
   }
 }