Revert of Mojo: Eliminate duplicate C API symbols

mojo/mojo_public.gyp

Index: mojo/mojo_public.gyp
diff --git a/mojo/mojo_public.gyp b/mojo/mojo_public.gyp
index ec5eb0eca412a168d885ff59794f3632507c2425..d73e4123f8ffee9c0d39b666c520baf3492a962b 100644
--- a/mojo/mojo_public.gyp
+++ b/mojo/mojo_public.gyp
@@ -3,13 +3,15 @@
 # found in the LICENSE file.
 
 {
+  'includes': [
+    'mojo_variables.gypi',
+  ],
   'target_defaults' : {
     'include_dirs': [
       '..',
     ],
   },
   'variables': {
-    'chromium_code': 1,
     'mojo_public_test_interfaces_mojom_files': [
       'public/interfaces/bindings/tests/math_calculator.mojom',
       'public/interfaces/bindings/tests/no_module.mojom',
@@ -34,15 +36,48 @@
       'type': 'none',
       'dependencies': [
         'mojo_js_bindings',
-        'mojo_public_system',
         'mojo_public_test_interfaces',
         'mojo_public_test_utils',
+        'mojo_system',
+      ],
+    },
+    {
+      # Targets that (a) need to obtain the settings that mojo_system passes on
+      # to its direct dependents but (b) are not themselves in a position to
+      # hardcode a dependency to mojo_system vs. mojo_system_impl (e.g.,
+      # because they are components) should depend on this target.
+      'target_name': 'mojo_system_placeholder',
+      'type': 'none',
+    },
+    {
+      'target_name': 'mojo_system',
+      'type': 'static_library',
+      'defines': [
+        'MOJO_SYSTEM_IMPLEMENTATION',
+      ],
+      'all_dependent_settings': {
+        'conditions': [
+          # We need to be able to call the MojoSetSystemThunks() function in
+          # system_thunks.cc
+          ['OS=="android"', {
+            'ldflags!': [
+              '-Wl,--exclude-libs=ALL',
+            ],
+          }],
+        ],
+      },
+      'sources': [
+        'public/platform/native/system_thunks.cc',
+        'public/platform/native/system_thunks.h',
+      ],
+      'dependencies': [
+        'mojo_system_headers',
       ],
     },
     {
       # GN version: //mojo/public/c/system
-      'target_name': 'mojo_public_system',
-      'type': '<(component)',
+      'target_name': 'mojo_system_headers',
+      'type': 'none',
       'sources': [
         'public/c/system/buffer.h',
         'public/c/system/core.h',
@@ -52,13 +87,8 @@
         'public/c/system/message_pipe.h',
         'public/c/system/platform_handle.h',
         'public/c/system/system_export.h',
-        'public/c/system/thunks.cc',
-        'public/c/systme/thunks.h',
         'public/c/system/types.h',
         'public/c/system/wait_set.h',
-      ],
-      'defines': [
-        'MOJO_SYSTEM_IMPLEMENTATION',
       ],
     },
     {
@@ -81,7 +111,7 @@
       ],
       'dependencies': [
         '../base/base.gyp:base',
-        'mojo_public_system',
+        'mojo_system_headers',
       ],
     },
     {
@@ -217,7 +247,7 @@
       'dependencies': [
         '../base/base.gyp:base',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
-        'mojo_cpp_system',
+        '<(mojo_system_for_component)',
       ],
       'export_dependent_settings': [
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',