Report lost context from GLES2Implementation based on share group state.

components/mus/gles2/command_buffer_local.cc

Index: components/mus/gles2/command_buffer_local.cc
diff --git a/components/mus/gles2/command_buffer_local.cc b/components/mus/gles2/command_buffer_local.cc
index 177c610243f1c68216ca4c7af54a3cb91b10b1c2..57359ebf38b0680727ea991a53115a37ff4f33ea 100644
--- a/components/mus/gles2/command_buffer_local.cc
+++ b/components/mus/gles2/command_buffer_local.cc
@@ -334,12 +334,6 @@ void CommandBufferLocal::SetLock(base::Lock* lock) {
   NOTIMPLEMENTED();
 }
 
-bool CommandBufferLocal::IsGpuChannelLost() {
-  DCHECK(CalledOnValidThread());
-  // This is only possible for out-of-process command buffers.
-  return false;
-}
-
 void CommandBufferLocal::EnsureWorkVisible() {
   // This is only relevant for out-of-process command buffers.
 }