Add helper function to generate a pair of ChannelHandles for ChannelM…

…ojo.

BUG=604282

Review-Url: https://codereview.chromium.org/2109213003
Cr-Commit-Position: refs/heads/master@{#403106}

ipc/ipc_channel.h

@@ -223,6 +223,17 @@ class IPC_EXPORT Channel : public Endpoint {
   static std::string GenerateVerifiedChannelID(const std::string& prefix);
 #endif
 
+  // Generates a pair of channel handles that can be used as the client and
+  // server ends of a ChannelMojo. |name_postfix| is appended to the end of the
+  // handle name to help identify the handles.
+  //
+  // Note, when using ChannelMojo, |ChannelHandle::name| serves no functional
+  // purpose other than to identify the channel in logging.
+  static void GenerateMojoChannelHandlePair(
+      const std::string& name_postfix,
+      IPC::ChannelHandle* handle0,
+      IPC::ChannelHandle* handle1);
+
 #if defined(OS_LINUX)
   // Sandboxed processes live in a PID namespace, so when sending the IPC hello
   // message from client to server we need to send the PID from the global

ipc/ipc_channel_common.cc

@@ -5,6 +5,7 @@
 #include "build/build_config.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_channel_mojo.h"
+#include "mojo/public/cpp/system/message_pipe.h"
 
 namespace IPC {
 
@@ -56,6 +57,30 @@ std::unique_ptr<Channel> Channel::CreateServer(
   return Channel::Create(channel_handle, Channel::MODE_SERVER, listener);
 }
 
+// static
+void Channel::GenerateMojoChannelHandlePair(
+    const std::string& name_postfix,
+    IPC::ChannelHandle* handle0,
+    IPC::ChannelHandle* handle1) {
+  DCHECK_NE(handle0, handle1);
+  // |name| is only used for logging and to aid developers in debugging. It
+  // doesn't _need_ to be unique, but this string is probably more useful than a
+  // generic "ChannelMojo".
+#if !defined(OS_NACL_SFI)
+  std::string name = "ChannelMojo-" + GenerateUniqueRandomChannelID();
+#else
+  std::string name = "ChannelMojo";
+#endif
+  if (!name_postfix.empty()) {
+    name += "-" + name_postfix;
+  }
+  mojo::MessagePipe message_pipe;
+  *handle0 = ChannelHandle(name);
+  handle0->mojo_handle = message_pipe.handle0.release();
+  *handle1 = ChannelHandle(name);
+  handle1->mojo_handle = message_pipe.handle1.release();
+}
+
 Channel::~Channel() {
 }