Add stubs for IPlugViewContentScaleSupport

src/plugin/bridges/vst3-impls/plug-view-proxy.cpp

@@ -186,3 +186,12 @@ tresult PLUGIN_API Vst3PlugViewProxyImpl::findParameter(
 
     return response.result;
 }
+
+tresult PLUGIN_API
+Vst3PlugViewProxyImpl::setContentScaleFactor(ScaleFactor factor) {
+    // TODO: Implement
+    bridge.logger.log(
+        "TODO: Implement "
+        "iplugviewcontentscalesupport::setContentScaleFactor()");
+    return Steinberg::kNotImplemented;
+}

src/plugin/bridges/vst3-impls/plug-view-proxy.h

@@ -63,6 +63,9 @@ class Vst3PlugViewProxyImpl : public Vst3PlugViewProxy {
                   int32 yPos,
                   Steinberg::Vst::ParamID& resultTag /*out*/) override;
 
+    // From `iplugviewcontentscalesupport`
+    tresult PLUGIN_API setContentScaleFactor(ScaleFactor factor) override;
+
     /**
      * The `IPlugFrame` object passed by the host passed to us in
      * `IPlugView::setFrame()`. When the plugin makes a callback on the