[WebGL 2] primitive restart should be always enabled

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index a11d2ec467d6643f507a35040f3335d5b25b3a7f..fe82cbb20e82a22f142068b62626c62b18cc5a29 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -6176,12 +6176,30 @@ void GLES2DecoderImpl::DoFramebufferRenderbuffer(
 
 void GLES2DecoderImpl::DoDisable(GLenum cap) {
   if (SetCapabilityState(cap, false)) {
+    if (cap == GL_PRIMITIVE_RESTART_FIXED_INDEX) {
+      // TODO(Yunchao): crbug.com/594021
+      // On Desktop GL with versions lower than 4.3, we need to emulate
+      // GL_PRIMITIVE_RESTART_FIXED_INDEX using glPrimitiveRestartIndex().
+      if (feature_info_->feature_flags().emulate_primitive_restart_fixed_index) {
+        return;
+      }
+      buffer_manager()->SetPrimitiveRestartState(false);
+    }
     glDisable(cap);
   }
 }
 
 void GLES2DecoderImpl::DoEnable(GLenum cap) {
   if (SetCapabilityState(cap, true)) {
+    if (cap == GL_PRIMITIVE_RESTART_FIXED_INDEX) {
+      // TODO(Yunchao): crbug.com/594021
+      // On Desktop GL with versions lower than 4.3, we need to emulate
+      // GL_PRIMITIVE_RESTART_FIXED_INDEX using glPrimitiveRestartIndex().
+      if (feature_info_->feature_flags().emulate_primitive_restart_fixed_index) {
+        return;
+      }
+      buffer_manager()->SetPrimitiveRestartState(true);
+    }
     glEnable(cap);
   }
 }