Disable synchronous resizing until a frame is produced (flutter/engine#22457)

Instead of synchronousResizing flag which in some cases seems to be set too early, synchronous resizing is postponed until framework produces a frame so ResizeSynchronizer knows for sure that the engine is up and running.

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine.mm

@@ -322,7 +322,6 @@ static bool OnAcquireExternalTexture(FlutterEngine* engine,
   [self sendUserLocales];
   [self updateWindowMetrics];
   [self updateDisplayConfig];
-  self.viewController.flutterView.synchronousResizing = YES;
   return YES;
 }
 
@@ -359,9 +358,6 @@ static bool OnAcquireExternalTexture(FlutterEngine* engine,
     [self shutDownEngine];
     _resourceContext = nil;
   }
-  if (_engine) {
-    self.viewController.flutterView.synchronousResizing = YES;
-  }
 }
 
 - (id<FlutterBinaryMessenger>)binaryMessenger {

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterResizeSynchronizer.mm

@@ -17,6 +17,10 @@
   // Used to block [requestCommit].
   std::condition_variable _condBlockRequestCommit;
 
+  // Whether a frame was received; We don't block platform thread during resize
+  // until we know that framework is running and producing frames
+  BOOL _receivedFirstFrame;
+
   // If NO, requestCommit calls are ignored until shouldEnsureSurfaceForSize is called with
   // proper size.
   BOOL _acceptingCommit;
@@ -50,6 +54,12 @@
     return;
   }
 
+  if (!_receivedFirstFrame) {
+    // No blocking until framework produces at least one frame
+    notify();
+    return;
+  }
+
   ++_cookie;
 
   // from now on, ignore all incoming commits until the block below gets
@@ -79,6 +89,11 @@
 
 - (BOOL)shouldEnsureSurfaceForSize:(CGSize)size {
   std::unique_lock<std::mutex> lock(_mutex);
+
+  if (!_receivedFirstFrame) {
+    return YES;
+  }
+
   if (!_acceptingCommit) {
     if (CGSizeEqualToSize(_newSize, size)) {
       _acceptingCommit = YES;
@@ -93,6 +108,8 @@
     return;
   }
 
+  _receivedFirstFrame = YES;
+
   _pendingCommit = YES;
   if (_waiting) {  // BeginResize is in progress, interrupt it and schedule commit call
     _condBlockRequestCommit.notify_all();

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h

@@ -25,13 +25,6 @@
  */
 @property(readwrite, nonatomic, nonnull) NSOpenGLContext* openGLContext;
 
-/**
- * Controls whether view resizing synchronously updates contents. This can only be enabled
- * after the engine is running and producing frames, because during synchronous view resizing the
- * platform thread is blocked until engine produces frame with requested size.
- */
-@property(readwrite, nonatomic) BOOL synchronousResizing;
-
 - (nullable instancetype)initWithFrame:(NSRect)frame
                           shareContext:(nonnull NSOpenGLContext*)shareContext
                        reshapeListener:(nonnull id<FlutterViewReshapeListener>)reshapeListener

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterView.mm

@@ -71,15 +71,11 @@
 }
 
 - (void)reshaped {
-  if (self.synchronousResizing) {
-    CGSize scaledSize = [self convertSizeToBacking:self.bounds.size];
-    [_resizeSynchronizer beginResize:scaledSize
-                              notify:^{
-                                [_reshapeListener viewDidReshape:self];
-                              }];
-  } else {
-    [_reshapeListener viewDidReshape:self];
-  }
+  CGSize scaledSize = [self convertSizeToBacking:self.bounds.size];
+  [_resizeSynchronizer beginResize:scaledSize
+                            notify:^{
+                              [_reshapeListener viewDidReshape:self];
+                            }];
 }
 
 #pragma mark - NSView overrides