PPAPI/NaCl: Make a gyp flag for including the untrusted IPC proxy.

This way, those of us working on the proxy switch need only add:
{
  'variables': {
    'build_ppapi_ipc_proxy_untrusted': '1',
  },
}
to "~/.gyp/include.gypi"

...and we'll be able to build our untrusted targets without editing all.gyp. For anybody who doesn't set that flag, our ppapi_proxy_untrusted.gypi file will still be parsed, but it doesn't matter if the source files build (or even exist).

BUG=116317
TEST=

Review URL: https://chromiumcodereview.appspot.com/10399068

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137751 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -273,6 +273,11 @@
       # plugins to make call of the main thread.
       'enable_pepper_threading%': 0,
 
+      # Include the PPAPI IPC proxy for NaCl. This is a work-in-progress; this
+      # allows us to build this feature locally without it affecting others
+      # working in affected subsystems like base and ipc.
+      'build_ppapi_ipc_proxy_untrusted%': 0,
+
       # Enables use of the session service, which is enabled by default.
       # Support for disabling depends on the platform.
       'enable_session_service%': 1,
@@ -523,6 +528,7 @@
     'use_gnome_keyring%': '<(use_gnome_keyring)',
     'linux_fpic%': '<(linux_fpic)',
     'enable_pepper_threading%': '<(enable_pepper_threading)',
+    'build_ppapi_ipc_proxy_untrusted%': '<(build_ppapi_ipc_proxy_untrusted)',
     'chromeos%': '<(chromeos)',
     'use_virtual_keyboard%': '<(use_virtual_keyboard)',
     'enable_viewport%': '<(enable_viewport)',

ppapi/ppapi.gyp

@@ -7,6 +7,11 @@
 # in the .gyp files (since ppapi_internal depends on parts of Chrome).
 
 {
+  'conditions': [
+    ['disable_nacl==0 and build_ppapi_ipc_proxy_untrusted==1', {
+      'includes': ['ppapi_proxy_untrusted.gypi'],
+    }],
+  ],
   'variables': {
     'chromium_code': 1,  # Use higher warning level.
   },