chore: fix ambiguous reference gcc compile error (#35734)

Co-authored-by: Bruno Pitrus <[email protected]>

shell/browser/serial/electron_serial_delegate.cc

@@ -66,16 +66,18 @@ device::mojom::SerialPortManager* ElectronSerialDelegate::GetPortManager(
   return GetChooserContext(frame)->GetPortManager();
 }
 
-void ElectronSerialDelegate::AddObserver(content::RenderFrameHost* frame,
-                                         Observer* observer) {
+void ElectronSerialDelegate::AddObserver(
+    content::RenderFrameHost* frame,
+    content::SerialDelegate::Observer* observer) {
   observer_list_.AddObserver(observer);
   auto* chooser_context = GetChooserContext(frame);
   if (!port_observation_.IsObserving())
     port_observation_.Observe(chooser_context);
 }
 
-void ElectronSerialDelegate::RemoveObserver(content::RenderFrameHost* frame,
-                                            Observer* observer) {
+void ElectronSerialDelegate::RemoveObserver(
+    content::RenderFrameHost* frame,
+    content::SerialDelegate::Observer* observer) {
   observer_list_.RemoveObserver(observer);
 }
 

shell/browser/serial/electron_serial_delegate.h

@@ -38,9 +38,9 @@ class ElectronSerialDelegate : public content::SerialDelegate,
   device::mojom::SerialPortManager* GetPortManager(
       content::RenderFrameHost* frame) override;
   void AddObserver(content::RenderFrameHost* frame,
-                   Observer* observer) override;
+                   content::SerialDelegate::Observer* observer) override;
   void RemoveObserver(content::RenderFrameHost* frame,
-                      Observer* observer) override;
+                      content::SerialDelegate::Observer* observer) override;
   void RevokePortPermissionWebInitiated(
       content::RenderFrameHost* frame,
       const base::UnguessableToken& token) override;