GN: Make content and content_shell work when !enable_plugins

content/BUILD.gn

Index: content/BUILD.gn
diff --git a/content/BUILD.gn b/content/BUILD.gn
index 30d4109246c5a02f3f67b5e2ec5af3abcfebe7d3..22c0332310e306b114157379f6507299bb8c6f6b 100644
--- a/content/BUILD.gn
+++ b/content/BUILD.gn
@@ -12,7 +12,6 @@ config("content_implementation") {
 content_shared_components = [
   "//content/gpu",
   "//content/plugin",
-  "//content/ppapi_plugin",
   "//content/public/browser:sources",
   "//content/public/child",
   "//content/public/common",
@@ -22,6 +21,10 @@ content_shared_components = [
   "//content/renderer",
 ]
 
+if (enable_plugins) {
+  content_shared_components += [ "//content/ppapi_plugin" ]
+}
+
 if (is_component_build) {
   shared_library("content") {
     deps = content_shared_components + [