Support pdfium compilation with xcode 10.11 and higher

build/standalone.gypi

 # 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.
 
 # Definitions to be used when building stand-alone PDFium binaries.
 
 {
   'variables': {
     'component%': 'static_library',
     'clang%': 0,
@@ skipping 396 matching lines @@
             },
           }],
         ],
       }],  # OS=="win"
       ['OS=="mac"', {
         'target_conditions': [
           ['_type!="static_library"', {
             'xcode_settings': {'OTHER_LDFLAGS': ['-Wl,-search_paths_first']},
           }],
         ],  # target_conditions
+        'variables': {
+          'mac_sdk_min': '10.10',
+          'mac_sdk%': '<!(python <(DEPTH)/build/gyp/tools/mac_find_sdk.py <(mac_sdk_min))',

[Nico, 2016/02/23 19:04:52]

this will silently use the newest sdk on the bots; is that what we want? i think
in chromium land we use find_sdk on developer machines but force a known result
on bots

[Wei Li, 2016/02/23 20:00:35]

Will bot use the same file as the mac_find_sdk in this CL? mac_find_sdk find the
oldest/smallest version which is equal or larger than the minimal sdk version.
In our case, if we have 10.10, we would always go with 10.10. On some machines
which don't have 10.10, we may go up to 10.11 or higher.  

+        },
+        'xcode_settings': {
+          'SDKROOT': 'macosx<(mac_sdk)',  # -isysroot
+          # See comment in Chromium's common.gypi for why this is needed.
+          'SYMROOT': '<(DEPTH)/xcodebuild',
+        },
       }],  # OS=="mac"
       ['v8_use_external_startup_data==1', {
         'defines': [
           'V8_USE_EXTERNAL_STARTUP_DATA',
         ],
       }],  # v8_use_external_startup_data==1
       ['clang==1 or host_clang==1', {
         # This is here so that all files get recompiled after a clang roll and
         # when turning clang on or off.
         # (defines are passed via the command line, and build systems rebuild
         # things when their commandline changes). Nothing should ever read this
         # define.
         'defines': ['CR_CLANG_REVISION=<!(python <(DEPTH)/tools/clang/scripts/update.py --print-revision)'],
       }],
     ],
   },
-  'xcode_settings': {
-    'SDKROOT': 'macosx10.10',  # -isysroot
-    # See comment in Chromium's common.gypi for why this is needed.
-    'SYMROOT': '<(DEPTH)/xcodebuild',
-  },
   'conditions': [
     ['OS=="linux" or OS=="mac"', {
       'conditions': [
         ['clang==1', {
           'make_global_settings': [
             ['CC', '<(clang_dir)/bin/clang'],
             ['CXX', '<(clang_dir)/bin/clang++'],
           ],
         }],
       ],
     }],  # OS=="linux" or OS=="mac"
     ["use_goma==1", {
       'make_global_settings': [
         ['CC_wrapper', '<(gomadir)/gomacc'],
         ['CXX_wrapper', '<(gomadir)/gomacc'],
       ],
     }],  # use_goma==1
   ],
 }