Provide access to the ID for the remoted Windows session in the network process

remoting/host/desktop_environment.h

Index: remoting/host/desktop_environment.h
diff --git a/remoting/host/desktop_environment.h b/remoting/host/desktop_environment.h
index ec984c5a4467316cf2a36673d66388f93e289093..a98281c29963a389b0932e50856183822a0924a8 100644
--- a/remoting/host/desktop_environment.h
+++ b/remoting/host/desktop_environment.h
@@ -5,6 +5,7 @@
 #ifndef REMOTING_HOST_DESKTOP_ENVIRONMENT_H_
 #define REMOTING_HOST_DESKTOP_ENVIRONMENT_H_
 
+#include <cstdint>
 #include <memory>
 #include <string>
 
@@ -53,6 +54,10 @@ class DesktopEnvironment {
   // Passes the final set of capabilities negotiated between the client and host
   // to |this|.
   virtual void SetCapabilities(const std::string& capabilities) = 0;
+
+  // Returns an id which identifies the current desktop session on Windows.
+  // Other platforms will always return the default value (UINT32_MAX).
+  virtual uint32_t GetDesktopSessionId() const = 0;
 };
 
 // Used to create |DesktopEnvironment| instances.