Allow compiling PDFium without V8.

samples/samples.gyp

 # Copyright 2014 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
+  'variables': {
+    'pdf_enable_v8%': 1,
+  },
   'target_defaults': {
     'defines' : [
       'PNG_PREFIX',
       'PNGPREFIX_H',
       'PNG_USE_READ_MACROS',
     ],
     'include_dirs': [
       '<(DEPTH)',
-      '<(DEPTH)/v8',
-      '<(DEPTH)/v8/include',
+    ],
+    'conditions': [
+      ['pdf_enable_v8==1', {
+        'include_dirs': [
+          '<(DEPTH)/v8',
+          '<(DEPTH)/v8/include',
+        ],
+      }],
     ],
   },
   'targets': [
     {
       'target_name': 'pdfium_test',
       'type': 'executable',
       'dependencies': [
         'fx_lpng',
         '../pdfium.gyp:pdfium',
         # Regardless of whether the library ships against system freetype,
         # always link this binary against the bundled one for consistency
         # of results across platforms.
         '../third_party/third_party.gyp:fx_freetype',
-        '<(DEPTH)/v8/tools/gyp/v8.gyp:v8_libplatform',
       ],
       'sources': [
         'pdfium_test.cc',
         'image_diff_png.cc',
       ],
       'link_settings': {
         'libraries!': [
           '-lfreetype',
         ],
       },
+      'conditions': [
+        ['pdf_enable_v8==1', {
+          'dependencies': [
+            '<(DEPTH)/v8/tools/gyp/v8.gyp:v8_libplatform',
+          ],
+        }],
+      ],
     },
     {
       'target_name': 'pdfium_diff',
       'type': 'executable',
       'variables': { 'enable_wexit_time_destructors': 1, },
       'dependencies': [
         'fx_lpng',
         '../pdfium.gyp:pdfium',
         '../third_party/third_party.gyp:pdfium_base',
       ],
@@ skipping 29 matching lines @@
         'fx_lpng/src/fx_pngset.c',
         'fx_lpng/src/fx_pngtrans.c',
         'fx_lpng/src/fx_pngwio.c',
         'fx_lpng/src/fx_pngwrite.c',
         'fx_lpng/src/fx_pngwtran.c',
         'fx_lpng/src/fx_pngwutil.c',
       ],
     },
   ],
 }