Move OneWriterSeqLock and SharedMemorySeqLockBuffer from content/ to device/base/synchronization

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index f764c0aa1157b405548d94dc31ab2d2be9be4b02..b5b5ab6037530a64b7f2b2e68c609147967f26fb 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -753,10 +753,13 @@ component("base") {
     "synchronization/lock_impl.h",
     "synchronization/lock_impl_posix.cc",
     "synchronization/lock_impl_win.cc",
+    "synchronization/one_writer_seqlock.cc",
+    "synchronization/one_writer_seqlock.h",
     "synchronization/read_write_lock.h",
     "synchronization/read_write_lock_nacl.cc",
     "synchronization/read_write_lock_posix.cc",
     "synchronization/read_write_lock_win.cc",
+    "synchronization/shared_memory_seqlock_buffer.h",
     "synchronization/spin_wait.h",
     "synchronization/waitable_event.h",
     "synchronization/waitable_event_posix.cc",
@@ -1924,6 +1927,7 @@ test("base_unittests") {
     "synchronization/atomic_flag_unittest.cc",
     "synchronization/condition_variable_unittest.cc",
     "synchronization/lock_unittest.cc",
+    "synchronization/one_writer_seqlock_unittest.cc",
     "synchronization/read_write_lock_unittest.cc",
     "synchronization/waitable_event_unittest.cc",
     "synchronization/waitable_event_watcher_unittest.cc",