Allow building of XFA branch without XFA

pdfium.gyp

 {
   'variables': {
     'pdf_use_skia%': 0,
+    'pdf_enable_xfa%': 1,
     'conditions': [
       ['OS=="linux"', {
         'bundle_freetype%': 0,
       }, {  # On Android there's no system FreeType. On Windows and Mac, only a
             # few methods are used from it.
         'bundle_freetype%': 1,
       }],
     ],
   },
   'target_defaults': {
     'defines' : [
       'OPJ_STATIC',
       'PNG_PREFIX',
       'PNGPREFIX_H',
       'PNG_USE_READ_MACROS',
       'V8_DEPRECATION_WARNINGS',
       '_CRT_SECURE_NO_WARNINGS',
     ],
     'include_dirs': [
       'third_party/freetype/include',
     ],
     'conditions': [
       ['pdf_use_skia==1', {
         'defines': ['_SKIA_SUPPORT_'],
       }],
+      ['pdf_enable_xfa==1', {
+        'defines': ['PDF_ENABLE_XFA'],
+      }],
       ['OS=="linux"', {
         'conditions': [
           ['target_arch=="x64"', {
             'defines' : [ '_FX_CPU_=_FX_X64_', ],
             'cflags': [ '-fPIC', ],
           }],
           ['target_arch=="ia32"', {
             'defines' : [ '_FX_CPU_=_FX_X86_', ],
           }],
         ],
@@ skipping 772 matching lines @@
         '<(DEPTH)'
       ],
       'sources': [
         'core/src/fxcodec/codec/fx_codec_jpx_unittest.cpp',
         'core/src/fxcrt/fx_basic_bstring_unittest.cpp',
         'core/src/fxcrt/fx_basic_memmgr_unittest.cpp',
         'core/src/fxcrt/fx_basic_wstring_unittest.cpp',
         'testing/fx_string_testhelpers.h',
         'testing/fx_string_testhelpers.cpp',
         'third_party/base/nonstd_unique_ptr_unittest.cpp',
-        'xfa/src/fxbarcode/pdf417/BC_PDF417HighLevelEncoder_unittest.cpp',
-        'xfa/src/fxfa/src/parser/xfa_utils_imp_unittest.cpp',
+      ],
+      'conditions': [
+        ['pdf_enable_xfa==1', {
+          'sources': [
+            'xfa/src/fxbarcode/pdf417/BC_PDF417HighLevelEncoder_unittest.cpp',
+            'xfa/src/fxfa/src/parser/xfa_utils_imp_unittest.cpp',
+          ],
+        }],
       ],
     },
     {
       'target_name': 'pdfium_embeddertests',
       'type': 'executable',
       'dependencies': [
         '<(DEPTH)/testing/gmock.gyp:gmock',
         '<(DEPTH)/testing/gtest.gyp:gtest',
         '<(DEPTH)/v8/tools/gyp/v8.gyp:v8_libplatform',
         'pdfium',
@@ skipping 17 matching lines @@
         'testing/embedder_test.cpp',
         'testing/embedder_test.h',
         'testing/embedder_test_mock_delegate.h',
         'testing/embedder_test_timer_handling_delegate.h',
         'testing/fx_string_testhelpers.cpp',
         'testing/fx_string_testhelpers.h',
       ],
     },
   ],
 }