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

blimp/client/core/switches/BUILD.gn

Index: blimp/client/core/switches/BUILD.gn
diff --git a/blimp/client/core/switches/BUILD.gn b/blimp/client/core/switches/BUILD.gn
index 00cc89edb215b68e113ebc9bc4d717bf9e7a030e..b3184f5611a0b710b5ca9f8617ca0404c481a45d 100644
--- a/blimp/client/core/switches/BUILD.gn
+++ b/blimp/client/core/switches/BUILD.gn
@@ -9,8 +9,9 @@ if (is_android) {
 
 source_set("switches") {
   visibility = [
-    "//blimp/client/*",
-    "//blimp/engine:browser_tests",
+    "//blimp/client/app:*",  # TODO(nyquist): Remove this. See crbug/651964.
+    "//blimp/client/core/*",
+    "//blimp/engine:browser_tests",  # TODO(nyquist): Remove this. See crbug/653789.
   ]
 
   sources = [
@@ -21,7 +22,7 @@ source_set("switches") {
 
 if (is_android) {
   android_library("switches_java") {
-    visibility = [ "//blimp/client/*" ]
+    visibility = [ "//blimp/client/core/*" ]
 
     java_files =
         [ "android/java/src/org/chromium/blimp/core/BlimpClientSwitches.java" ]