Add some remoting targets to GN build.

Since GN runs its scripts in a different current directory than GYP, I had to update the remoting html template script to be able to handle this situation.

Also includes many misc linking fixes:
  - Sets enable_nacl to false.
  - Add renderer context menu component
  - Adds many missing files

R=sergeyu@chromium.org

Review URL: https://codereview.chromium.org/498773005

Cr-Original-Commit-Position: refs/heads/master@{#291731}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1c693998d75f78e94862c324afba3815356ecaf1

config/features.gni

@@ -22,7 +22,9 @@ declare_args() {
   enable_plugins = !is_android || !is_ios
 
   # Enables Native Client support.
-  enable_nacl = (!is_ios && !is_android)
+  # TODO(GYP) enable this when nacl works in GN.
+  enable_nacl = false
+  #enable_nacl = (!is_ios && !is_android)
 
   # If debug_devtools is set to true, JavaScript files for DevTools are stored
   # as is and loaded from disk. Otherwise, a concatenated file is stored in