[api] Remove unowned Extensions interface

Extensions are now always passed via unique_ptr and are owned by V8.
This CL removes the deprecated API where the embedder would own the
Extension, but has no mechanism for deleting it.

R=ulan@chromium.org

Bug: v8:8725
Change-Id: Icb83660fad9d04c66f8db2265091ebabcbb197c4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1514493Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60186}

include/v8.h

@@ -6497,10 +6497,6 @@ class V8_EXPORT Extension {  // NOLINT
   bool auto_enable_;
 };
 
-V8_DEPRECATED(
-    "Use unique_ptr version or stop using extension (http://crbug.com/334679).",
-    void V8_EXPORT RegisterExtension(Extension* extension));
-
 void V8_EXPORT RegisterExtension(std::unique_ptr<Extension>);
 
 // --- Statics ---

src/api.cc

@@ -899,19 +899,9 @@ void V8::SetFlagsFromCommandLine(int* argc, char** argv, bool remove_flags) {
 
 RegisteredExtension* RegisteredExtension::first_extension_ = nullptr;
 
-RegisteredExtension::RegisteredExtension(Extension* extension)
-    : legacy_unowned_extension_(extension) {}
-
 RegisteredExtension::RegisteredExtension(std::unique_ptr<Extension> extension)
     : extension_(std::move(extension)) {}
 
-// static
-void RegisteredExtension::Register(Extension* extension) {
-  RegisteredExtension* new_extension = new RegisteredExtension(extension);
-  new_extension->next_ = first_extension_;
-  first_extension_ = new_extension;
-}
-
 // static
 void RegisteredExtension::Register(std::unique_ptr<Extension> extension) {
   RegisteredExtension* new_extension =
@@ -947,8 +937,6 @@ class ExtensionResource : public String::ExternalOneByteStringResource {
 };
 }  // anonymous namespace
 
-void RegisterExtension(Extension* that) { RegisteredExtension::Register(that); }
-
 void RegisterExtension(std::unique_ptr<Extension> extension) {
   RegisteredExtension::Register(std::move(extension));
 }

src/api.h

@@ -71,20 +71,14 @@ class ApiFunction {
 
 class RegisteredExtension {
  public:
-  static void Register(Extension*);
   static void Register(std::unique_ptr<Extension>);
   static void UnregisterAll();
-  Extension* extension() const {
-    return legacy_unowned_extension_ ? legacy_unowned_extension_
-                                     : extension_.get();
-  }
+  Extension* extension() const { return extension_.get(); }
   RegisteredExtension* next() const { return next_; }
   static RegisteredExtension* first_extension() { return first_extension_; }
  private:
   explicit RegisteredExtension(Extension*);
   explicit RegisteredExtension(std::unique_ptr<Extension>);
-  // TODO(clemensh): Remove this after the 7.4 branch.
-  Extension* legacy_unowned_extension_ = nullptr;
   std::unique_ptr<Extension> extension_;
   RegisteredExtension* next_ = nullptr;
   static RegisteredExtension* first_extension_;