[Sync] Add sync_export.h (Step 1 for componentizing sync)

sync/sync.gyp

 # Copyright (c) 2012 The Chromium 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': {
     'chromium_code': 1,
   },
   'targets': [
     # The core sync library.
     #
     # TODO(akalin): Rename this to something like 'sync_core' and
     # reserve the 'sync' name for the overarching library that clients
     # should depend on.
     {
       'target_name': 'sync',
+      # TODO(akalin): Change this to '<(component)'.  When we rename
+      # this to 'sync_core' and make the overarching 'sync' library,
+      # make that one '<(component)'.
       'type': 'static_library',

[Ryan Sleevi, 2012/07/12 18:22:13]

I don't think this CL will/should work unless/until you do change this to
<(component)

When building as a shared library, COMPONENT_BUILD will be set by
build/common.gypi. As a result, all of the symbols marked SYNC_EXPORT will be
marked declexport (when building this static lib), but marked declimport by all
dependents. As such, there will be confusion between whether or not the symbol
is really within the module, and multiple (dependent) modules may end up
inadvertantly exporting the same symbols.

[akalin, 2012/07/13 00:51:43]

I added '0 &&' to sync_export.h, so it should be a no-op for now.

       'variables': { 'enable_wexit_time_destructors': 1, },
       'include_dirs': [
         '..',
       ],
+      'defines': [
+        'SYNC_IMPLEMENTATION',
+      ],
       'dependencies': [
         '../base/base.gyp:base',
         '../build/temp_gyp/googleurl.gyp:googleurl',
         '../crypto/crypto.gyp:crypto',
         '../net/net.gyp:net',
         '../sql/sql.gyp:sql',
         'protocol/sync_proto.gyp:sync_proto',
       ],
       'export_dependent_settings': [
         # Propagate sync_proto since our headers include its generated
         # files.
         'protocol/sync_proto.gyp:sync_proto',
       ],
       'sources': [
+        'base/sync_export.h',
         'internal_api/public/base/enum_set.h',
         'internal_api/public/base/model_type.h',
         'internal_api/public/base/model_type_payload_map.cc',
         'internal_api/public/base/model_type_payload_map.h',
         'internal_api/public/engine/model_safe_worker.cc',
         'internal_api/public/engine/model_safe_worker.h',
         'internal_api/public/engine/passive_model_worker.cc',
         'internal_api/public/engine/passive_model_worker.h',
         'internal_api/public/engine/polling_constants.cc',
         'internal_api/public/engine/polling_constants.h',
@@ skipping 723 matching lines @@
       ],
       'sources': [
         'tools/sync_listen_notifications.cc',
       ],
     },
 
     # A standalone command-line sync client.
     {
       'target_name': 'sync_client',
       'type': 'executable',
+      'defines': [
+        'SYNC_TEST',
+      ],
       'dependencies': [
         '../base/base.gyp:base',
         '../jingle/jingle.gyp:notifier',
         '../net/net.gyp:net',
         '../net/net.gyp:net_test_support',
         'sync',
         'sync_notifier',
         'syncapi_core',
       ],
       'sources': [
@@ skipping 17 matching lines @@
             'test_suite_name': 'sync_unit_tests',
             'input_shlib_path': '<(SHARED_LIB_DIR)/<(SHARED_LIB_PREFIX)sync_unit_tests<(SHARED_LIB_SUFFIX)',
             'input_jars_paths': [ '<(PRODUCT_DIR)/lib.java/chromium_base.jar', ],
           },
           'includes': [ '../build/apk_test.gypi' ],
         },
       ],
     }],
   ],
 }