Add stubs in platform_macos and file_system_watcher_macos for building the same

runtime/bin/file_system_watcher_macos.cc

Index: runtime/bin/file_system_watcher_macos.cc
diff --git a/runtime/bin/file_system_watcher_macos.cc b/runtime/bin/file_system_watcher_macos.cc
index 2e24122b60b619c7a72a3b85d36c509badf9469b..3ebaf4f077329a4162721d77933aa0a0b9ab7e88 100644
--- a/runtime/bin/file_system_watcher_macos.cc
+++ b/runtime/bin/file_system_watcher_macos.cc
@@ -3,10 +3,10 @@
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
-#if defined(TARGET_OS_MACOS)
-
 #include "bin/file_system_watcher.h"
 
+#if defined(TARGET_OS_MACOS) && !defined(TARGET_OS_IOS)

[Ivan Posva, 2015/06/09 21:20:03]

This will not work on the regular Dart builds as they do not filter source files
and thus would always include the above line.

Preferable in this case would be:

#include "platform/globals.h"

#if defined(TARGET_OS_MACOS)
#include "bin/file_system_watcher.h"

#if !defined(TARGET_OS_IOS)

... original code ...

#else  // !defined(TARGET_OS_IOS)

... new stubbed out code ...

#endif // !defined(TARGET_OS_IOS)

+
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <unistd.h>  // NOLINT
@@ -393,3 +393,43 @@ Dart_Handle FileSystemWatcher::ReadEvents(intptr_t id, intptr_t path_id) {
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)
+
+#if defined(TARGET_OS_IOS)
+
+namespace dart {
+namespace bin {
+
+// FSEvents are unavailable on iOS. Stub out related methods
+Dart_Handle FileSystemWatcher::ReadEvents(intptr_t id, intptr_t path_id) {
+  return DartUtils::NewDartOSError();
+}
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id, intptr_t path_id) {
+  return -1;
+}
+
+bool FileSystemWatcher::IsSupported() {
+  return false;
+}
+
+void FileSystemWatcher::UnwatchPath(intptr_t id, intptr_t path_id) {
+}
+
+intptr_t FileSystemWatcher::Init() {
+  return -1;
+}
+
+void FileSystemWatcher::Close(intptr_t id) {
+}
+
+intptr_t FileSystemWatcher::WatchPath(intptr_t id,
+                                      const char* path,
+                                      int events,
+                                      bool recursive) {
+  return -1;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // defined(TARGET_OS_IOS)