[Chromecast] Split chromecast/net target to avoid unneeded deps includes

Split //chromecast/net:net to allow code to use ConnectivityChecker
alone without additional dependencies.

Bug: internal b/146520104
Merge-With: eureka-internal/345308
Test: compiled on several different builds
Change-Id: I15ca6d84cd88f635e03f20b5b329b9804a14eea7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974862
Commit-Queue: Marzena Dell'Aquila <mdellaquila@google.com>
Reviewed-by: Luke Halliwell (slow) <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726460}

chromecast/browser/BUILD.gn

@@ -186,6 +186,7 @@ cast_source_set("browser") {
     "//chromecast/media/service",
     "//chromecast/media/service/mojom",
     "//chromecast/net",
+    "//chromecast/net:connectivity_checker",
     "//chromecast/service",
     "//components/download/public/common:public",
     "//components/metrics",

chromecast/net/BUILD.gn

@@ -7,14 +7,6 @@ import("//testing/test.gni")
 
 cast_source_set("net") {
   sources = [
-    "connectivity_checker.cc",
-    "connectivity_checker.h",
-    "connectivity_checker_impl.cc",
-    "connectivity_checker_impl.h",
-    "fake_connectivity_checker.cc",
-    "fake_connectivity_checker.h",
-    "net_switches.cc",
-    "net_switches.h",
     "net_util_cast.cc",
     "net_util_cast.h",
   ]
@@ -27,15 +19,11 @@ cast_source_set("net") {
   }
 
   deps = [
+    ":net_switches",
     "//base",
-    "//chromecast:chromecast_buildflags",
     "//chromecast/base:cast_sys_info_util",
-    "//chromecast/base/metrics",
     "//chromecast/public",
-    "//components/proxy_config",
     "//net",
-    "//services/network/public/cpp",
-    "//services/network/public/mojom",
   ]
 
   if (is_fuchsia) {
@@ -51,6 +39,32 @@ cast_source_set("net") {
   }
 }
 
+cast_source_set("net_switches") {
+  sources = [
+    "net_switches.cc",
+    "net_switches.h",
+  ]
+}
+
+cast_source_set("connectivity_checker") {
+  sources = [
+    "connectivity_checker.cc",
+    "connectivity_checker.h",
+    "connectivity_checker_impl.cc",
+    "connectivity_checker_impl.h",
+    "fake_connectivity_checker.cc",
+    "fake_connectivity_checker.h",
+  ]
+  deps = [
+    ":net_switches",
+    "//base",
+    "//chromecast:chromecast_buildflags",
+    "//chromecast/base/metrics",
+    "//services/network/public/cpp",
+    "//services/network/public/mojom",
+  ]
+}
+
 cast_source_set("io_buffer_pool") {
   sources = [
     "io_buffer_pool.cc",