WebContent: Add IPC call to set window handle from WebContent client

Userland/Libraries/LibWeb/HTML/BrowsingContext.h

@@ -268,6 +268,7 @@ public:
     Optional<AK::URL> const& creator_url() const { return m_creator_url; }
 
     String const& window_handle() const { return m_window_handle; }
+    void set_window_handle(String handle) { m_window_handle = move(handle); }
 
 private:
     explicit BrowsingContext(Page&, HTML::BrowsingContextContainer*);

Userland/Services/WebContent/ConnectionFromClient.cpp

@@ -66,6 +66,11 @@ Messages::WebContentServer::GetWindowHandleResponse ConnectionFromClient::get_wi
     return m_page_host->page().top_level_browsing_context().window_handle();
 }
 
+void ConnectionFromClient::set_window_handle(String const& handle)
+{
+    m_page_host->page().top_level_browsing_context().set_window_handle(handle);
+}
+
 void ConnectionFromClient::connect_to_webdriver(DeprecatedString const& webdriver_ipc_path)
 {
     // FIXME: Propagate this error back to the browser.

Userland/Services/WebContent/ConnectionFromClient.h

@@ -49,6 +49,7 @@ private:
     Web::Page const& page() const;
 
     virtual Messages::WebContentServer::GetWindowHandleResponse get_window_handle() override;
+    virtual void set_window_handle(String const& handle) override;
     virtual void connect_to_webdriver(DeprecatedString const& webdriver_ipc_path) override;
     virtual void update_system_theme(Core::AnonymousBuffer const&) override;
     virtual void update_system_fonts(DeprecatedString const&, DeprecatedString const&, DeprecatedString const&) override;

Userland/Services/WebContent/WebContentServer.ipc

@@ -10,6 +10,7 @@
 endpoint WebContentServer
 {
     get_window_handle() => (String handle)
+    set_window_handle(String handle) =|
 
     connect_to_webdriver(DeprecatedString webdriver_ipc_path) =|