Update ArrayBuffer to use new BackingStore API (fixes issue #3074)

libcef/renderer/v8_impl.cc

@@ -329,9 +329,7 @@ class V8TrackArrayBuffer : public CefTrackNode {
   }
 
   ~V8TrackArrayBuffer() {
-    if (buffer_ != nullptr) {
-      release_callback_->ReleaseBuffer(buffer_);
-    }
+    ReleaseBuffer();
     isolate_->AdjustAmountOfExternalAllocatedMemory(
         -static_cast<int>(sizeof(V8TrackArrayBuffer)));
   }
@@ -340,6 +338,13 @@ class V8TrackArrayBuffer : public CefTrackNode {
     return release_callback_;
   }
 
+  void ReleaseBuffer() {
+    if (buffer_ && release_callback_) {
+      release_callback_->ReleaseBuffer(buffer_);
+    }
+    Detach();
+  }
+
   void Detach() { buffer_ = nullptr; }
 
   // Attach this track object to the specified V8 object.
@@ -1410,7 +1415,18 @@ CefRefPtr<CefV8Value> CefV8Value::CreateArrayBuffer(
   // released when the V8 object is destroyed.
   V8TrackArrayBuffer* tracker =
       new V8TrackArrayBuffer(isolate, buffer, release_callback);
-  v8::Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, buffer, length);
+
+  auto deleter = [](void* data, size_t length, void* deleter_data) {
+    auto* tracker = reinterpret_cast<V8TrackArrayBuffer*>(deleter_data);
+    if (tracker) {
+      tracker->ReleaseBuffer();
+    }
+  };
+
+  std::unique_ptr<v8::BackingStore> backing =
+      v8::ArrayBuffer::NewBackingStore(buffer, length, deleter, tracker);
+  v8::Local<v8::ArrayBuffer> ab =
+      v8::ArrayBuffer::New(isolate, std::move(backing));
 
   // Attach the tracker object.
   tracker->AttachTo(context, ab);

tests/ceftests/v8_unittest.cc

@@ -577,13 +577,18 @@ class V8RendererTest : public ClientAppRenderer::Delegate,
                        ->GetArrayBufferReleaseCallback()
                        .get()) == release_callback);
 
+      // |neuteredValue| buffer is explicitly freed by NeuterArrayBuffer().
+      EXPECT_FALSE(neuteredReleaseBufferCalled);
       EXPECT_TRUE(neuteredValue->NeuterArrayBuffer());
+      EXPECT_TRUE(neuteredReleaseBufferCalled);
+
+      // |value| buffer is implicitly freed when the value goes out of scope.
+      EXPECT_FALSE(releaseBufferCalled);
     }
     // Exit the V8 context.
     EXPECT_TRUE(destructorCalled);
     EXPECT_TRUE(releaseBufferCalled);
     EXPECT_TRUE(neuteredDestructorCalled);
-    EXPECT_FALSE(neuteredReleaseBufferCalled);
     EXPECT_TRUE(context->Exit());
     DestroyTest();
   }