[Multiwindow, macOS] FlutterCompositor::Present receives view_id (flutter#37391)

* Impl and test

* Change to default view

Author: dkwingsmt

shell/platform/darwin/macos/framework/Source/FlutterCompositor.h

@@ -47,10 +47,12 @@ class FlutterCompositor {
   virtual bool CollectBackingStore(
       const FlutterBackingStore* backing_store) = 0;
 
-  // Presents the FlutterLayers by updating FlutterView(s) using the
-  // layer content.
+  // Presents the FlutterLayers by updating the FlutterView specified by
+  // `view_id` using the layer content.
   // Present sets frame_started_ to false.
-  virtual bool Present(const FlutterLayer** layers, size_t layers_count) = 0;
+  virtual bool Present(uint64_t view_id,
+                       const FlutterLayer** layers,
+                       size_t layers_count) = 0;
 
   using PresentCallback = std::function<bool(bool has_flutter_content)>;
 

shell/platform/darwin/macos/framework/Source/FlutterEngine.mm

@@ -458,7 +458,11 @@ - (FlutterCompositor*)createFlutterCompositor {
                                            size_t layers_count,          //
                                            void* user_data               //
                                         ) {
-    return reinterpret_cast<flutter::FlutterCompositor*>(user_data)->Present(layers, layers_count);
+    // TODO(dkwingsmt): This callback only supports single-view, therefore it
+    // only operates on the default view. To support multi-view, we need a new
+    // callback that also receives a view ID.
+    return reinterpret_cast<flutter::FlutterCompositor*>(user_data)->Present(kFlutterDefaultViewId,
+                                                                             layers, layers_count);
   };
 
   _compositor.avoid_backing_store_cache = true;

shell/platform/darwin/macos/framework/Source/FlutterMetalCompositor.h

@@ -40,9 +40,12 @@ class FlutterMetalCompositor : public FlutterCompositor {
   // for this FlutterBackingStore object in CreateBackingStore.
   bool CollectBackingStore(const FlutterBackingStore* backing_store) override;
 
-  // Composites the provided FlutterLayer objects and presents the composited
-  // frame to the FlutterView(s).
-  bool Present(const FlutterLayer** layers, size_t layers_count) override;
+  // Presents the FlutterLayers by updating the FlutterView specified by
+  // `view_id` using the layer content.
+  // Present sets frame_started_ to false.
+  bool Present(uint64_t view_id,
+               const FlutterLayer** layers,
+               size_t layers_count) override;
 
  private:
   // Presents the platform view layer represented by `layer`. `layer_index` is

shell/platform/darwin/macos/framework/Source/FlutterMetalCompositor.mm

@@ -80,11 +80,10 @@
   return true;
 }
 
-bool FlutterMetalCompositor::Present(const FlutterLayer** layers, size_t layers_count) {
-  // TODO(dkwingsmt): This class only supports single-view for now. As more
-  // classes are gradually converted to multi-view, it should get the view ID
-  // from somewhere.
-  FlutterView* view = GetView(kFlutterDefaultViewId);
+bool FlutterMetalCompositor::Present(uint64_t view_id,
+                                     const FlutterLayer** layers,
+                                     size_t layers_count) {
+  FlutterView* view = GetView(view_id);
   if (!view) {
     return false;
   }

shell/platform/darwin/macos/framework/Source/FlutterMetalCompositorUnittests.mm

@@ -73,7 +73,7 @@ - (nullable FlutterView*)getView:(uint64_t)viewId {
     return true;
   });
 
-  ASSERT_TRUE(macos_compositor->Present(nil, 0));
+  ASSERT_TRUE(macos_compositor->Present(0, nil, 0));
   ASSERT_TRUE(flag);
 }