Add PPB_ImageData to untrusted NaCl build.

ppapi/ppapi_proxy_untrusted.gypi

Index: ppapi/ppapi_proxy_untrusted.gypi
===================================================================
--- ppapi/ppapi_proxy_untrusted.gypi	(revision 138154)
+++ ppapi/ppapi_proxy_untrusted.gypi	(working copy)
@@ -256,7 +256,7 @@
           'shared_impl/ppb_file_io_shared.cc',
           'shared_impl/ppb_file_ref_shared.cc',
 #          'shared_impl/ppb_graphics_3d_shared.cc',
-#          'shared_impl/ppb_image_data_shared.cc',
+          'shared_impl/ppb_image_data_shared.cc',
           'shared_impl/ppb_input_event_shared.cc',
           'shared_impl/ppb_instance_shared.cc',
           'shared_impl/ppb_memory_shared.cc',
@@ -311,7 +311,7 @@
 #          'thunk/ppb_graphics_3d_thunk.cc',
 #          'thunk/ppb_graphics_3d_trusted_thunk.cc',
 #          'thunk/ppb_host_resolver_private_thunk.cc',
-#          'thunk/ppb_image_data_thunk.cc',
+          'thunk/ppb_image_data_thunk.cc',
 #          'thunk/ppb_image_data_trusted_thunk.cc',
           'thunk/ppb_instance_thunk.cc',
 #          'thunk/ppb_layer_compositor_thunk.cc',
@@ -365,7 +365,7 @@
 #          'proxy/ppb_graphics_2d_proxy.cc',
 #          'proxy/ppb_graphics_3d_proxy.cc',
 #          'proxy/ppb_host_resolver_private_proxy.cc',
-#          'proxy/ppb_image_data_proxy.cc',
+          'proxy/ppb_image_data_proxy.cc',
           'proxy/ppb_instance_proxy.cc',
           'proxy/ppb_message_loop_proxy.cc',
 #          'proxy/ppb_network_monitor_private_proxy.cc',