Own Web fallback services and trim Win32 session state

src/platform_legacy/legacy_platform_state.cpp

@@ -19,12 +19,22 @@ struct RetainedLegacyStoragePaths final {
     pp::platform::PlatformStoragePaths storage_paths;
 };
 
+struct RetainedLegacyWebPlatformServicesBinding final {
+    pp::platform::WebPlatformServices* services = nullptr;
+};
+
 [[nodiscard]] RetainedLegacyStoragePaths& retained_legacy_storage_paths()
 {
     static RetainedLegacyStoragePaths state;
     return state;
 }
 
+[[nodiscard]] RetainedLegacyWebPlatformServicesBinding& retained_legacy_web_platform_services_binding()
+{
+    static RetainedLegacyWebPlatformServicesBinding state;
+    return state;
+}
+
 class RetainedWebPlatformServices final : public pp::platform::WebPlatformServices {
 public:
     void publish_exported_image(std::string_view path) override
@@ -94,10 +104,23 @@ void request_legacy_glfw_app_close()
 
 [[nodiscard]] pp::platform::WebPlatformServices& active_legacy_web_platform_services()
 {
+    if (auto* services = retained_legacy_web_platform_services_binding().services)
+        return *services;
+
     static RetainedWebPlatformServices services;
     return pp::platform::resolve_web_platform_services(services);
 }
 
+[[nodiscard]] std::unique_ptr<pp::platform::WebPlatformServices> create_legacy_web_platform_services()
+{
+    return std::make_unique<RetainedWebPlatformServices>();
+}
+
+void set_legacy_web_platform_services(pp::platform::WebPlatformServices* services)
+{
+    retained_legacy_web_platform_services_binding().services = services;
+}
+
 [[nodiscard]] bool handles_legacy_web_platform_family(pp::platform::PlatformFamily family) noexcept
 {
     return family == pp::platform::PlatformFamily::webgl;

src/platform_legacy/legacy_platform_state.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <memory>
+
 #include "platform_api/platform_policy.h"
 #include "platform_api/platform_services.h"
 
@@ -22,6 +24,8 @@ void request_legacy_glfw_app_close();
 #endif
 
 [[nodiscard]] pp::platform::WebPlatformServices& active_legacy_web_platform_services();
+[[nodiscard]] std::unique_ptr<pp::platform::WebPlatformServices> create_legacy_web_platform_services();
+void set_legacy_web_platform_services(pp::platform::WebPlatformServices* services);
 [[nodiscard]] bool handles_legacy_web_platform_family(pp::platform::PlatformFamily family) noexcept;
 void publish_legacy_web_exported_image(std::string_view path);
 [[nodiscard]] bool try_publish_legacy_web_exported_image(