[mojo] Add CreateSharedBuffer method to Broker.

mojo/edk/system/child_broker_host.h

Index: mojo/edk/system/child_broker_host.h
diff --git a/mojo/edk/system/child_broker_host.h b/mojo/edk/system/child_broker_host.h
index 943ff13e280f47296477f17c41c41c05a9bec21e..3e6c377308e84581fe1ec703c23fc062fcac1699 100644
--- a/mojo/edk/system/child_broker_host.h
+++ b/mojo/edk/system/child_broker_host.h
@@ -21,15 +21,15 @@ namespace mojo {
 namespace edk {
 
 // Responds to requests from ChildBroker. This is used to handle message pipe
-// multiplexing and Windows sandbox messages. There is one object of this class
+// multiplexing and sandbox messages. There is one object of this class
 // per child process host object.
 // This object will delete itself when it notices that the pipe is broken.
 class MOJO_SYSTEM_IMPL_EXPORT ChildBrokerHost
-    : public RawChannel::Delegate
+    : public RawChannel::Delegate,
 #if defined(OS_WIN)
-      , NON_EXPORTED_BASE(public base::MessageLoopForIO::IOHandler) {
+      NON_EXPORTED_BASE(public base::MessageLoopForIO::IOHandler) {
 #else
-    {
+      public base::MessageLoopForIO::Watcher {
 #endif
  public:
   // |child_process| is a handle to the child process. It will be duplicated by
@@ -75,6 +75,13 @@ class MOJO_SYSTEM_IMPL_EXPORT ChildBrokerHost
   // Helper wrappers around DuplicateHandle.
   HANDLE DuplicateToChild(HANDLE handle);
   HANDLE DuplicateFromChild(HANDLE handle);
+#else
+  void DoRead();
+  void DoWrite();
+
+  // base::MessageLoopForIO::Watcher implementation:
+  void OnFileCanReadWithoutBlocking(int fd) override;
+  void OnFileCanWriteWithoutBlocking(int fd) override;
 #endif
 
   base::ProcessId process_id_;
@@ -82,22 +89,24 @@ class MOJO_SYSTEM_IMPL_EXPORT ChildBrokerHost
   // Channel used to receive and send multiplexing related messages.
   RoutedRawChannel* child_channel_;
 
-#if defined(OS_WIN)
-  // Handle to the child process, used for duplication of handles.
-  base::Process child_process_;
-
   // Pipe used for synchronous messages from the child. Responses are written to
   // it as well.
   ScopedPlatformHandle sync_channel_;
 
+#if defined(OS_WIN)
+  // Handle to the child process, used for duplication of handles.
+  base::Process child_process_;
+  std::vector<char> write_data_;
   base::MessageLoopForIO::IOContext read_context_;
   base::MessageLoopForIO::IOContext write_context_;
+#else
+  std::deque<PlatformHandle> write_handles_;
+  base::MessageLoopForIO::FileDescriptorWatcher fd_controller_;
+#endif
 
   std::vector<char> read_data_;
   // How many bytes in read_data_ we already read.
   uint32_t num_bytes_read_;
-  std::vector<char> write_data_;
-#endif
 
   DISALLOW_COPY_AND_ASSIGN(ChildBrokerHost);
 };