Revert of Update mojo sdk to rev 8af2ccff2eee4bfca1043015abee30482a030b30

third_party/mojo/src/mojo/public/go/system/core.go

Index: third_party/mojo/src/mojo/public/go/system/core.go
diff --git a/third_party/mojo/src/mojo/public/go/system/core.go b/third_party/mojo/src/mojo/public/go/system/core.go
index da6313e0be764076e2b69fa6fdaa5b181b290dfb..e1b8cd4d50a37ef40f7859e9f435e6122537902a 100644
--- a/third_party/mojo/src/mojo/public/go/system/core.go
+++ b/third_party/mojo/src/mojo/public/go/system/core.go
@@ -9,7 +9,6 @@
 import "C"
 import (
 	"reflect"
-	"sync"
 	"unsafe"
 )
 
@@ -58,21 +57,8 @@
 
 // coreImpl is an implementation of the Mojo system APIs.
 type coreImpl struct {
-	// Protects from making parallel non-blocking mojo cgo calls.
-	mu sync.Mutex
 }
 
-// GetCore returns singleton instance of the Mojo system APIs implementation.
-//
-// The implementation uses cgo to call native mojo APIs implementation. Each cgo
-// call uses a separate thread for execution. To limit the number of used
-// threads all non-blocking system calls (i.e. all system calls except |Wait|
-// and |WaitMany|) on this implementation and on handles returned by this
-// implementation are protected by a mutex so that if you make two parallel
-// system calls one will wait for another to finish before executing.
-// However, |Wait| and |WaitMany| are not protected by a mutex and each parallel
-// call will use a separate thread. To reduce number of threads used for |Wait|
-// calls prefer to use |WaitMany|.
 func GetCore() Core {
 	return &core
 }
@@ -82,13 +68,10 @@
 }
 
 func (impl *coreImpl) AcquireNativeHandle(handle MojoHandle) UntypedHandle {
-	return &untypedHandleImpl{baseHandle{impl, handle}}
+	return &untypedHandleImpl{baseHandle{handle}}
 }
 
 func (impl *coreImpl) GetTimeTicksNow() MojoTimeTicks {
-	impl.mu.Lock()
-	defer impl.mu.Unlock()
-
 	return MojoTimeTicks(C.MojoGetTimeTicksNow())
 }
 
@@ -125,9 +108,6 @@
 }
 
 func (impl *coreImpl) CreateDataPipe(opts *DataPipeOptions) (MojoResult, ProducerHandle, ConsumerHandle) {
-	impl.mu.Lock()
-	defer impl.mu.Unlock()
-
 	cParams := C.MallocCreateDataPipeParams()
 	defer C.FreeCreateDataPipeParams(cParams)
 	result := C.MojoCreateDataPipe(opts.cValue(cParams.opts), cParams.producer, cParams.consumer)
@@ -137,9 +117,6 @@
 }
 
 func (impl *coreImpl) CreateMessagePipe(opts *MessagePipeOptions) (MojoResult, MessagePipeHandle, MessagePipeHandle) {
-	impl.mu.Lock()
-	defer impl.mu.Unlock()
-
 	cParams := C.MallocCreateMessagePipeParams()
 	defer C.FreeCreateMessagePipeParams(cParams)
 	result := C.MojoCreateMessagePipe(opts.cValue(cParams.opts), cParams.handle0, cParams.handle1)
@@ -149,9 +126,6 @@
 }
 
 func (impl *coreImpl) CreateSharedBuffer(opts *SharedBufferOptions, numBytes uint64) (MojoResult, SharedBufferHandle) {
-	impl.mu.Lock()
-	defer impl.mu.Unlock()
-
 	cParams := C.MallocCreateSharedBufferParams()
 	defer C.FreeCreateSharedBufferParams(cParams)
 	result := C.MojoCreateSharedBuffer(opts.cValue(cParams.opts), C.uint64_t(numBytes), cParams.handle)