[mojo] Add CreateSharedBuffer method to Broker.

mojo/edk/system/child_broker_host.h

 // Copyright 2015 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.
 
 #ifndef MOJO_EDK_SYSTEM_CHILD_BROKER_HOST_H_
 #define MOJO_EDK_SYSTEM_CHILD_BROKER_HOST_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/process.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/routed_raw_channel.h"
 #include "mojo/edk/system/system_impl_export.h"
 
 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
   // this object. |pipe| is a handle to the communication pipe to the child
   // process, which is generated inside mojo::edk::ChildProcessLaunched. It is
   // owned by this class.
   ChildBrokerHost(base::ProcessHandle child_process, ScopedPlatformHandle pipe);
 
   base::ProcessId GetProcessId();
 
@@ skipping 29 matching lines @@
   void BeginRead();
 
   // base::MessageLoopForIO::IOHandler implementation:
   void OnIOCompleted(base::MessageLoopForIO::IOContext* context,
                      DWORD bytes_transferred,
                      DWORD error) override;
 
   // Helper wrappers around DuplicateHandle.
   HANDLE DuplicateToChild(HANDLE handle);
   HANDLE DuplicateFromChild(HANDLE handle);
+#else
+  // Reads all currently available data, and responds to any completed messages.
+  void TryReadAndWriteHandles();
+
+  // base::MessageLoopForIO::Watcher implementation:
+  void OnFileCanReadWithoutBlocking(int fd) override;
+  void OnFileCanWriteWithoutBlocking(int fd) override;
 #endif
 
   base::ProcessId process_id_;
 
   // 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);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_CHILD_BROKER_HOST_H_