Make mojo_system static and mojo_system_impl a component, never use both

mojo/shell/in_process_dynamic_service_runner.cc

 // Copyright 2014 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.
 
 #include "mojo/shell/in_process_dynamic_service_runner.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/scoped_native_library.h"
+#include "mojo/public/platform/native/system_thunks.h"
 
 namespace mojo {
 namespace shell {
 
 InProcessDynamicServiceRunner::InProcessDynamicServiceRunner(
     Context* /*context*/)
     : thread_(this, "app_thread") {
 }
 
 InProcessDynamicServiceRunner::~InProcessDynamicServiceRunner() {
@@ skipping 32 matching lines @@
   do {
     base::NativeLibraryLoadError error;
     base::ScopedNativeLibrary app_library(
         base::LoadNativeLibrary(app_path_, &error));
     if (!app_library.is_valid()) {
       LOG(ERROR) << "Failed to load library (error: " << error.ToString()
                  << ")";
       break;
     }
 
+    MojoSetSystemThunksFn mojo_set_system_thunks_fn =
+        reinterpret_cast<MojoSetSystemThunksFn>(app_library.GetFunctionPointer(
+            "MojoSetSystemThunks"));
+    if (mojo_set_system_thunks_fn) {
+      MojoSystemThunks system_thunks = MojoMakeSystemThunks();
+      size_t expected_size = mojo_set_system_thunks_fn(&system_thunks);
+      if (expected_size > sizeof(MojoSystemThunks)) {
+        LOG(ERROR)
+            << "Invalid DSO. Expected MojoSystemThunks size: "
+            << expected_size;
+        break;
+      }
+    }
+
     typedef MojoResult (*MojoMainFunction)(MojoHandle);
     MojoMainFunction main_function = reinterpret_cast<MojoMainFunction>(
         app_library.GetFunctionPointer("MojoMain"));
     if (!main_function) {
       LOG(ERROR) << "Entrypoint MojoMain not found";
       break;
     }
 
     // |MojoMain()| takes ownership of the service handle.
     MojoResult result = main_function(service_handle_.release().value());
     if (result < MOJO_RESULT_OK)
       LOG(ERROR) << "MojoMain returned an error: " << result;
   } while (false);
 
   bool success = app_completed_callback_runner_.Run();
   app_completed_callback_runner_.Reset();
   LOG_IF(ERROR, !success) << "Failed post run app_completed_callback";
 }
 
 }  // namespace shell
 }  // namespace mojo