DCHECK if shader compilation fails that it's due to context loss.

mojo/gles2/command_buffer_client_impl.cc

Index: mojo/gles2/command_buffer_client_impl.cc
diff --git a/mojo/gles2/command_buffer_client_impl.cc b/mojo/gles2/command_buffer_client_impl.cc
index 69336791a0d27419e9a57918223cc945b56db987..837ec9cbdf4b45293a5799857d97eb38f1076cbd 100644
--- a/mojo/gles2/command_buffer_client_impl.cc
+++ b/mojo/gles2/command_buffer_client_impl.cc
@@ -335,4 +335,9 @@ void CommandBufferClientImpl::MakeProgressAndUpdateState() {
 void CommandBufferClientImpl::SetLock(base::Lock* lock) {
 }
 
+void CommandBufferClientImpl::IsGpuChannelLost() {
+  // This is only possible for out-of-process command buffers.
+  return false;
+}
+
 }  // namespace gles2