Move content::MakeSharedMemorySegmentViaIPC into its own file

content/common/child_process_sandbox_support_impl_linux.cc

Index: content/common/child_process_sandbox_support_impl_linux.cc
diff --git a/content/common/child_process_sandbox_support_impl_linux.cc b/content/common/child_process_sandbox_support_impl_linux.cc
index 4e7b1f0f5d3c1f6843512e7e373d03460657efcd..ca3a351a9d0cf2c413934055fbb04d216191d4a2 100644
--- a/content/common/child_process_sandbox_support_impl_linux.cc
+++ b/content/common/child_process_sandbox_support_impl_linux.cc
@@ -87,21 +87,6 @@ void GetRenderStyleForStrike(const char* family, int sizeAndStyle,
   }
 }
 
-int MakeSharedMemorySegmentViaIPC(size_t length, bool executable) {
-  Pickle request;
-  request.WriteInt(LinuxSandbox::METHOD_MAKE_SHARED_MEMORY_SEGMENT);
-  request.WriteUInt32(length);
-  request.WriteBool(executable);
-  uint8_t reply_buf[10];
-  int result_fd;
-  ssize_t result = UnixDomainSocket::SendRecvMsg(GetSandboxFD(),
-                                                 reply_buf, sizeof(reply_buf),
-                                                 &result_fd, request);
-  if (result == -1)
-    return -1;
-  return result_fd;
-}
-
 int MatchFontWithFallback(const std::string& face, bool bold,
                           bool italic, int charset) {
   Pickle request;