Don't set -fvisibility=hidden for iOS Debug.

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 5055 matching lines @@
           'CLANG_LINK_OBJC_RUNTIME': 'NO',          # -fno-objc-link-runtime
           'COPY_PHASE_STRIP': 'NO',
           'GCC_C_LANGUAGE_STANDARD': 'c99',         # -std=c99
           'GCC_CW_ASM_SYNTAX': 'NO',                # No -fasm-blocks
           'GCC_ENABLE_CPP_EXCEPTIONS': 'NO',        # -fno-exceptions
           'GCC_ENABLE_CPP_RTTI': 'NO',              # -fno-rtti
           'GCC_ENABLE_PASCAL_STRINGS': 'NO',        # No -mpascal-strings
           # GCC_INLINES_ARE_PRIVATE_EXTERN maps to -fvisibility-inlines-hidden
           'GCC_INLINES_ARE_PRIVATE_EXTERN': 'YES',
           'GCC_OBJC_CALL_CXX_CDTORS': 'YES',        # -fobjc-call-cxx-cdtors
-          'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',      # -fvisibility=hidden
           'GCC_THREADSAFE_STATICS': 'NO',           # -fno-threadsafe-statics
           'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES',    # -Werror
           'GCC_VERSION': '4.2',
           'GCC_WARN_ABOUT_MISSING_NEWLINE': 'YES',  # -Wnewline-eof
           'USE_HEADERMAP': 'NO',
           'WARNING_CFLAGS': [
             '-Wall',
             '-Wextra',
             # Don't warn about unused function parameters.
             '-Wno-unused-parameter',
@@ skipping 41 matching lines @@
               'OTHER_CFLAGS': [
                 '-Xclang', '-add-plugin', '-Xclang', '<(clang_add_plugin)',
               ],
             }],
             ['clang==1 and "<(GENERATOR)"=="ninja"', {
               'OTHER_CFLAGS': [
                 # See http://crbug.com/110262
                 '-fcolor-diagnostics',
               ],
             }],
-            ['OS=="ios" and target_subarch!="arm32" and \
-              "<(GENERATOR)"=="xcode"', {
-              'OTHER_CFLAGS': [
-                # TODO(ios): when building Chrome for iOS on 64-bit platform
-                # with Xcode, the -Wshorted-64-to-32 warning is automatically
-                # enabled. This cause failures when compiling protobuf code,
-                # so disable the warning. http://crbug.com/359107
-                '-Wno-shorten-64-to-32',
+            ['OS=="ios"', {
+              'configurations': {
+                'Debug': {
+                  # XCTests inject a dynamic library into the application. If
+                  # fvisibility is set to hidden, then some symbols needed by
+                  # XCTests are not available. Disable this setting for
+                  # Debug configuration.
+                  'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
+                },
+                'Release': {
+                  'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',    # -fvisibility=hidden
+                },
+              },
+              'conditions': [
+                ['target_subarch!="arm32" and "<(GENERATOR)"=="xcode"', {
+                  'OTHER_CFLAGS': [
+                    # TODO(ios): when building Chrome for iOS on 64-bit
+                    # platform with Xcode, the -Wshorted-64-to-32 warning is
+                    # automatically enabled. This causes failures when
+                    # compiling protobuf code, so disable the warning.
+                    # http://crbug.com/359107
+                    '-Wno-shorten-64-to-32',
+                  ],
+                }],
               ],
             }],
+            ['OS=="mac"', {
+              'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',    # -fvisibility=hidden
+            }],
           ],
         },
         'conditions': [
           ['clang==1', {
             'variables': {
               'clang_dir': '../third_party/llvm-build/Release+Asserts/bin',
             },
           }],
           ['asan==1', {
             'xcode_settings': {
@@ skipping 1251 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }