Add platform view support for linux

ci/licenses_golden/licenses_flutter

@@ -2057,6 +2057,12 @@ FILE: ../../../flutter/shell/platform/linux/fl_pixel_buffer_texture_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_pixel_buffer_texture_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_platform_plugin.cc
 FILE: ../../../flutter/shell/platform/linux/fl_platform_plugin.h
+FILE: ../../../flutter/shell/platform/linux/fl_platform_view.cc
+FILE: ../../../flutter/shell/platform/linux/fl_platform_view_factory.cc
+FILE: ../../../flutter/shell/platform/linux/fl_platform_view_private.h
+FILE: ../../../flutter/shell/platform/linux/fl_platform_views_plugin.cc
+FILE: ../../../flutter/shell/platform/linux/fl_platform_views_plugin.h
+FILE: ../../../flutter/shell/platform/linux/fl_platform_views_plugin_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registrar.cc
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registrar_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registrar_test.cc
@@ -2110,6 +2116,8 @@ FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_method_chann
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_method_codec.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_method_response.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_pixel_buffer_texture.h
+FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_platform_view.h
+FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_platform_view_factory.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_plugin_registrar.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_plugin_registry.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_standard_message_codec.h

shell/platform/linux/BUILD.gn

@@ -57,6 +57,8 @@ _public_headers = [
   "public/flutter_linux/fl_method_codec.h",
   "public/flutter_linux/fl_method_response.h",
   "public/flutter_linux/fl_pixel_buffer_texture.h",
+  "public/flutter_linux/fl_platform_view.h",
+  "public/flutter_linux/fl_platform_view_factory.h",
   "public/flutter_linux/fl_plugin_registrar.h",
   "public/flutter_linux/fl_plugin_registry.h",
   "public/flutter_linux/fl_standard_message_codec.h",
@@ -121,6 +123,9 @@ source_set("flutter_linux_sources") {
     "fl_mouse_cursor_plugin.cc",
     "fl_pixel_buffer_texture.cc",
     "fl_platform_plugin.cc",
+    "fl_platform_view.cc",
+    "fl_platform_view_factory.cc",
+    "fl_platform_views_plugin.cc",
     "fl_plugin_registrar.cc",
     "fl_plugin_registry.cc",
     "fl_renderer.cc",
@@ -194,6 +199,7 @@ executable("flutter_linux_unittests") {
     "fl_method_codec_test.cc",
     "fl_method_response_test.cc",
     "fl_pixel_buffer_texture_test.cc",
+    "fl_platform_views_plugin_test.cc",
     "fl_plugin_registrar_test.cc",
     "fl_standard_message_codec_test.cc",
     "fl_standard_method_codec_test.cc",
@@ -205,6 +211,7 @@ executable("flutter_linux_unittests") {
     "testing/mock_binary_messenger_response_handle.cc",
     "testing/mock_engine.cc",
     "testing/mock_epoxy.cc",
+    "testing/mock_platform_view.cc",
     "testing/mock_plugin_registrar.cc",
     "testing/mock_renderer.cc",
     "testing/mock_text_input_plugin.cc",

shell/platform/linux/fl_platform_view.cc

@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_platform_view_factory.h"
+
+#include "flutter/shell/platform/linux/fl_platform_view_private.h"
+
+#include <gmodule.h>
+
+// Added here to stop the compiler from optimizing this function away.
+G_MODULE_EXPORT GType fl_platform_view_get_type();
+
+typedef struct {
+  GtkTextDirection direction;
+} FlPlatformViewPrivate;
+
+G_DEFINE_TYPE_WITH_PRIVATE(FlPlatformView, fl_platform_view, G_TYPE_OBJECT)
+
+static void fl_platform_view_class_init(FlPlatformViewClass* klass) {}
+
+static void fl_platform_view_init(FlPlatformView* self) {}
+
+G_MODULE_EXPORT GtkWidget* fl_platform_view_get_view(FlPlatformView* self) {
+  g_return_val_if_fail(FL_IS_PLATFORM_VIEW(self), nullptr);
+
+  GtkWidget* widget = FL_PLATFORM_VIEW_GET_CLASS(self)->get_view(self);
+  if (!widget || !GTK_IS_WIDGET(widget)) {
+    g_critical("fl_platform_view::get_view should return GtkWidget");
+    return nullptr;
+  }
+
+  FlPlatformViewPrivate* priv = static_cast<FlPlatformViewPrivate*>(
+      fl_platform_view_get_instance_private(self));
+  gtk_widget_set_direction(widget, priv->direction);
+
+  return widget;
+}
+
+void fl_platform_view_set_direction(FlPlatformView* self,
+                                    GtkTextDirection direction) {
+  FlPlatformViewPrivate* priv = static_cast<FlPlatformViewPrivate*>(
+      fl_platform_view_get_instance_private(self));
+  priv->direction = direction;
+}

shell/platform/linux/fl_platform_view_factory.cc

@@ -0,0 +1,39 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_platform_view_factory.h"
+
+#include <gmodule.h>
+
+// Added here to stop the compiler from optimizing this function away.
+G_MODULE_EXPORT GType fl_platform_view_factory_get_type();
+
+G_DEFINE_INTERFACE(FlPlatformViewFactory,
+                   fl_platform_view_factory,
+                   G_TYPE_OBJECT)
+
+static void fl_platform_view_factory_default_init(
+    FlPlatformViewFactoryInterface* iface) {}
+
+G_MODULE_EXPORT FlPlatformView* fl_platform_view_factory_create_platform_view(
+    FlPlatformViewFactory* self,
+    int64_t view_identifier,
+    FlValue* args) {
+  g_return_val_if_fail(FL_IS_PLATFORM_VIEW_FACTORY(self), nullptr);
+
+  return FL_PLATFORM_VIEW_FACTORY_GET_IFACE(self)->create_platform_view(
+      self, view_identifier, args);
+}
+
+G_MODULE_EXPORT FlMessageCodec*
+fl_platform_view_factory_get_create_arguments_codec(
+    FlPlatformViewFactory* self) {
+  g_return_val_if_fail(FL_IS_PLATFORM_VIEW_FACTORY(self), nullptr);
+
+  if (!FL_PLATFORM_VIEW_FACTORY_GET_IFACE(self)->get_create_arguments_codec)
+    return nullptr;
+
+  return FL_PLATFORM_VIEW_FACTORY_GET_IFACE(self)->get_create_arguments_codec(
+      self);
+}

shell/platform/linux/fl_platform_view_private.h

@@ -0,0 +1,24 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_VIEW_PRIVATE_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_VIEW_PRIVATE_H_
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_platform_view.h"
+
+G_BEGIN_DECLS
+
+/**
+ * fl_platform_view_set_direction:
+ * @platform_view: an #FlPlatformView.
+ * @direction: new #GtkTextDirection for platform view.
+ *
+ * Set text direction.
+ */
+void fl_platform_view_set_direction(FlPlatformView* platform_view,
+                                    GtkTextDirection direction);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_VIEW_PRIVATE_H_