Bug 1706374 - Part 9: Allow reading OtherPid() from an opened IPC::Channel, r=handyman

This will be used to handle pre-opened channels more reliably in ports code.

Differential Revision: https://phabricator.services.mozilla.com/D112774

ipc/chromium/src/chrome/common/ipc_channel.h

@@ -12,6 +12,7 @@
 #include "base/basictypes.h"
 #include "build/build_config.h"
 #include "mozilla/UniquePtr.h"
+#include "chrome/common/ipc_message.h"
 
 #ifdef OS_WIN
 #  include <string>
@@ -121,6 +122,10 @@ class Channel {
   // immediately.
   bool Send(mozilla::UniquePtr<Message> message);
 
+  // The PID which this channel has been opened with. This will be
+  // `-1` until `OnChannelConnected` has been called.
+  int32_t OtherPid() const;
+
   // Unsound_IsClosed() and Unsound_NumQueuedMessages() are safe to call from
   // any thread, but the value returned may be out of date, because we don't
   // use any synchronization when reading or writing it.

ipc/chromium/src/chrome/common/ipc_channel_posix.cc

@@ -965,6 +965,8 @@ void Channel::CloseClientFileDescriptor() {
   channel_impl_->CloseClientFileDescriptor();
 }
 
+int32_t Channel::OtherPid() const { return channel_impl_->OtherPid(); }
+
 bool Channel::Unsound_IsClosed() const {
   return channel_impl_->Unsound_IsClosed();
 }

ipc/chromium/src/chrome/common/ipc_channel_posix.h

@@ -51,6 +51,8 @@ class Channel::ChannelImpl : public MessageLoopForIO::Watcher {
   int GetFileDescriptor() const { return pipe_; }
   void CloseClientFileDescriptor();
 
+  int32_t OtherPid() const { return other_pid_; }
+
   // See the comment in ipc_channel.h for info on Unsound_IsClosed() and
   // Unsound_NumQueuedMessages().
   bool Unsound_IsClosed() const;

ipc/chromium/src/chrome/common/ipc_channel_win.cc

@@ -624,6 +624,8 @@ bool Channel::Send(mozilla::UniquePtr<Message> message) {
   return channel_impl_->Send(std::move(message));
 }
 
+int32_t Channel::OtherPid() const { return channel_impl_->OtherPid(); }
+
 bool Channel::Unsound_IsClosed() const {
   return channel_impl_->Unsound_IsClosed();
 }

ipc/chromium/src/chrome/common/ipc_channel_win.h

@@ -46,6 +46,8 @@ class Channel::ChannelImpl : public MessageLoopForIO::IOHandler {
   }
   bool Send(mozilla::UniquePtr<Message> message);
 
+  int32_t OtherPid() const { return other_pid_; }
+
   // See the comment in ipc_channel.h for info on Unsound_IsClosed() and
   // Unsound_NumQueuedMessages().
   bool Unsound_IsClosed() const;