Move some global feature defines to buildflags

Moves
  enable_captive_portal_detection
  enable_hangout_services_extension
  enable_plugin_installation
out of the global features.gni files and moves them into chrome/common's
feature flags buildflag header. This increases encapsulation and reduces the
global #defines passed to all compiles.

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation
TBR=jschuh (render_messages.h)

Review-Url: https://codereview.chromium.org/2405013002
Cr-Commit-Position: refs/heads/master@{#424659}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index be206b18..813b1cc 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -3945,7 +3945,12 @@
 grit("resources") {
   source = "browser_resources.grd"
   use_qualified_include = true
+
   defines = chrome_grit_defines
+  if (enable_hangout_services_extension) {
+    defines += [ "enable_hangout_services_extension" ]
+  }
+
   output_dir = "$root_gen_dir/chrome"
   outputs = [
     "grit/browser_resources.h",