Split ios/chrome/app/startup targets to reduce dependencies.

ios/chrome/browser/BUILD.gn

Index: ios/chrome/browser/BUILD.gn
diff --git a/ios/chrome/browser/BUILD.gn b/ios/chrome/browser/BUILD.gn
index de6beb485d0686e18387ea6dfbb98fedc1383be5..7779b4780ae89d3bbf1bfd503ba69b857d169af2 100644
--- a/ios/chrome/browser/BUILD.gn
+++ b/ios/chrome/browser/BUILD.gn
@@ -8,6 +8,20 @@ import("//build/config/ios/rules.gni")
 import("//rlz/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
+source_set("chrome_paths") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  sources = [
+    "chrome_paths.h",
+    "chrome_paths.mm",
+    "chrome_paths_internal.h",
+  ]
+
+  deps = [
+    "//base",
+    "//components/gcm_driver",
+  ]
+}
+
 source_set("browser") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
@@ -25,9 +39,6 @@ source_set("browser") {
     "chrome_constants.h",
     "chrome_coordinator.h",
     "chrome_coordinator.mm",
-    "chrome_paths.h",
-    "chrome_paths.mm",
-    "chrome_paths_internal.h",
     "chrome_root_coordinator.h",
     "chrome_root_coordinator.mm",
     "chrome_switches.cc",
@@ -66,6 +77,7 @@ source_set("browser") {
     "xcallback_parameters.h",
     "xcallback_parameters.mm",
   ]
+
   deps = [
     ":settings_resources",
     "//base",
@@ -74,7 +86,6 @@ source_set("browser") {
     "//components/dom_distiller/core",
     "//components/flags_ui",
     "//components/flags_ui:switches",
-    "//components/gcm_driver",
     "//components/handoff",
     "//components/keyed_service/core",
     "//components/keyed_service/ios",
@@ -112,6 +123,9 @@ source_set("browser") {
     "//rlz/features",
     "//url",
   ]
+  public_deps = [
+    ":chrome_paths",
+  ]
   allow_circular_includes_from = [
     "//ios/chrome/browser/sync/glue",
     "//ios/chrome/browser/browser_state",