Add remaining trivial targets for the Linux GN build

This patch adds a whole bunch of small targets that
had either already been done but weren't mentioned
in the 'gn_all' group, or needed to be done.

In theory this should produce no change on any platform
other than Linux, except for one small windows target.

[email protected]
[email protected]
BUG=432959
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Review URL: https://codereview.chromium.org/975123003

Cr-Commit-Position: refs/heads/master@{#319580}
diff --git a/content/BUILD.gn b/content/BUILD.gn
index be1f456c..e31ea82 100644
--- a/content/BUILD.gn
+++ b/content/BUILD.gn
@@ -80,3 +80,18 @@
     "content/common/content_export.h",
   ]
 }
+
+if (is_win) {
+  source_set("content_startup_helper_win") {
+    sources = [
+      "app/startup_helper_win.cc",
+      "public/app/startup_helper_win.h",
+    ]
+
+    deps = [
+      "//base",
+      "//base:i18n",
+      "//sandbox",
+    ]
+  }
+}
diff --git a/content/content.gyp b/content/content.gyp
index 3d73378c..a5d4829c 100644
--- a/content/content.gyp
+++ b/content/content.gyp
@@ -31,6 +31,7 @@
     ['OS == "win"', {
       'targets': [
         {
+          # GN: //content:content_startup_helper_win
           'target_name': 'content_startup_helper_win',
           'type': 'static_library',
           'include_dirs': [