[dart:ui] Add view ID to PointerData.toString (#51352)

The `view_id` is useful information as the pointer's `x` and `y` coordinates are relative to the view's origin.

Part of flutter/flutter#112205
Part of flutter/flutter#142845

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: loic-sharma

lib/ui/pointer.dart

@@ -381,7 +381,7 @@ class PointerData {
   final double rotation;
 
   @override
-  String toString() => 'PointerData(x: $physicalX, y: $physicalY)';
+  String toString() => 'PointerData(viewId: $viewId, x: $physicalX, y: $physicalY)';
 
   /// Returns a complete textual description of the information in this object.
   String toStringFull() {

lib/ui/window/platform_configuration.h

@@ -481,13 +481,13 @@ class PlatformConfiguration final {
   void ReportTimings(std::vector<int64_t> timings);
 
   //----------------------------------------------------------------------------
-  /// @brief      Retrieves the Window with the given ID managed by the
-  ///             `PlatformConfiguration`.
+  /// @brief      Retrieves the viewport metrics with the given ID managed by
+  ///             the `PlatformConfiguration`.
   ///
-  /// @param[in] window_id The id of the window to find and return.
+  /// @param[in]  view_id The id of the view's viewport metrics to return.
   ///
-  /// @return     a pointer to the Window. Returns nullptr if the ID is not
-  ///             found.
+  /// @return     a pointer to the ViewportMetrics. Returns nullptr if the ID is
+  ///             not found.
   ///
   const ViewportMetrics* GetMetrics(int view_id);
 

lib/web_ui/lib/pointer.dart

@@ -111,7 +111,7 @@ class PointerData {
   final double rotation;
 
   @override
-  String toString() => 'PointerData(x: $physicalX, y: $physicalY)';
+  String toString() => 'PointerData(viewId: $viewId, x: $physicalX, y: $physicalY)';
   String toStringFull() {
     return '$runtimeType('
            'embedderId: $embedderId, '

shell/platform/embedder/tests/embedder_unittests.cc

@@ -2700,7 +2700,7 @@ TEST_F(EmbedderTest, CanSendPointer) {
       CREATE_NATIVE_ENTRY([&message_latch](Dart_NativeArguments args) {
         auto message = tonic::DartConverter<std::string>::FromDart(
             Dart_GetNativeArgument(args, 0));
-        ASSERT_EQ("PointerData(x: 123.0, y: 456.0)", message);
+        ASSERT_EQ("PointerData(viewId: 0, x: 123.0, y: 456.0)", message);
         message_latch.Signal();
       }));
 
@@ -2715,6 +2715,7 @@ TEST_F(EmbedderTest, CanSendPointer) {
   pointer_event.x = 123;
   pointer_event.y = 456;
   pointer_event.timestamp = static_cast<size_t>(1234567890);
+  pointer_event.view_id = 0;
 
   FlutterEngineResult result =
       FlutterEngineSendPointerEvent(engine.get(), &pointer_event, 1);