Add a Linux Shell that uses GTK for rendering.

ci/licenses_golden/licenses_flutter

@@ -1132,6 +1132,11 @@ FILE: ../../../flutter/shell/platform/glfw/platform_handler.h
 FILE: ../../../flutter/shell/platform/glfw/public/flutter_glfw.h
 FILE: ../../../flutter/shell/platform/glfw/text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/glfw/text_input_plugin.h
+FILE: ../../../flutter/shell/platform/linux/fl_dart_project.cc
+FILE: ../../../flutter/shell/platform/linux/fl_view.cc
+FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_dart_project.h
+FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_view.h
+FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/flutter_linux.h
 FILE: ../../../flutter/shell/platform/windows/angle_surface_manager.cc
 FILE: ../../../flutter/shell/platform/windows/angle_surface_manager.h
 FILE: ../../../flutter/shell/platform/windows/client_wrapper/flutter_view_controller.cc

shell/platform/linux/BUILD.gn

@@ -5,15 +5,23 @@
 assert(is_linux)
 
 import("//flutter/shell/platform/glfw/config.gni")
+import("//flutter/shell/platform/linux/config.gni")
 
 group("linux") {
+  deps = []
   if (build_glfw_shell) {
-    deps = [
+    deps += [
       ":flutter_linux_glfw",
       "//flutter/shell/platform/glfw:publish_headers_glfw",
       "//flutter/shell/platform/glfw/client_wrapper:publish_wrapper_glfw",
     ]
   }
+  if (build_linux_shell) {
+    deps += [
+      ":flutter_linux_gtk",
+      ":publish_headers_linux",
+    ]
+  }
 }
 
 # Temporary workaround for the issue describe in
@@ -37,3 +45,49 @@ if (build_glfw_shell) {
     public_configs = [ "//flutter:config" ]
   }
 }
+
+if (build_linux_shell) {
+  _public_headers = [
+    "public/flutter_linux/fl_dart_project.h",
+    "public/flutter_linux/fl_view.h",
+    "public/flutter_linux/flutter_linux.h",
+  ]
+
+  config("relative_flutter_linux_headers") {
+    include_dirs = [ "public" ]
+  }
+
+  source_set("flutter_linux") {
+    sources = [
+      "fl_dart_project.cc",
+      "fl_view.cc",
+    ]
+
+    configs += [
+      "//flutter/shell/platform/linux/config:gtk",
+      "//flutter/shell/platform/linux/config:egl",
+    ]
+
+    # Set flag to stop headers being directly included (library users should not do this)
+    defines = [ "FLUTTER_LINUX_COMPILATION" ]
+
+    deps = [
+      "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    ]
+  }
+
+  shared_library("flutter_linux_gtk") {
+    deps = [
+      ":flutter_linux",
+    ]
+
+    public_configs = [ "//flutter:config" ]
+  }
+
+  copy("publish_headers_linux") {
+    sources = _public_headers
+    outputs = [
+      "$root_out_dir/flutter_linux/{{source_file_part}}",
+    ]
+  }
+}

shell/platform/linux/config.gni

@@ -0,0 +1,11 @@
+# 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.
+
+declare_args() {
+  # Whether to build the Linux (GTK) shell for the host platform, if available.
+  #
+  # The Linux shell is not currently built by default as the CI system doesn't
+  # (yet) have GTK as a dependency. When that is ready the flag will be removed.
+  build_linux_shell = false
+}

shell/platform/linux/config/BUILD.gn

@@ -3,7 +3,17 @@
 # found in the LICENSE file.
 
 import("//build/config/linux/pkg_config.gni")
+import("//flutter/shell/platform/linux/config.gni")
 
 pkg_config("x11") {
   packages = [ "x11" ]
 }
+
+if (build_linux_shell) {
+  pkg_config("gtk") {
+    packages = [ "gtk+-3.0" ]
+  }
+  pkg_config("egl") {
+    packages = [ "egl" ]
+  }
+}

shell/platform/linux/fl_dart_project.cc

@@ -0,0 +1,140 @@
+// 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_dart_project.h"
+
+#include <gmodule.h>
+
+/**
+ * FlDartProject:
+ *
+ * #FlDartProject represents a Dart project. It is used provide information
+ * about the application when creating a #FlView.
+ */
+
+struct _FlDartProject {
+  GObject parent_instance;
+
+  gchar* assets_path;
+  gchar* icu_data_path;
+};
+
+enum { PROP_ASSETS_PATH = 1, PROP_ICU_DATA_PATH, PROP_LAST };
+
+G_DEFINE_TYPE(FlDartProject, fl_dart_project, G_TYPE_OBJECT)
+
+static void fl_dart_project_set_property(GObject* object,
+                                         guint prop_id,
+                                         const GValue* value,
+                                         GParamSpec* pspec) {
+  FlDartProject* self = FL_DART_PROJECT(object);
+
+  switch (prop_id) {
+    case PROP_ASSETS_PATH:
+      g_free(self->assets_path);
+      self->assets_path = g_strdup(g_value_get_string(value));
+      break;
+    case PROP_ICU_DATA_PATH:
+      g_free(self->icu_data_path);
+      self->icu_data_path = g_strdup(g_value_get_string(value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+      break;
+  }
+}
+
+static void fl_dart_project_get_property(GObject* object,
+                                         guint prop_id,
+                                         GValue* value,
+                                         GParamSpec* pspec) {
+  FlDartProject* self = FL_DART_PROJECT(object);
+
+  switch (prop_id) {
+    case PROP_ASSETS_PATH:
+      g_value_set_string(value, self->assets_path);
+      break;
+    case PROP_ICU_DATA_PATH:
+      g_value_set_string(value, self->icu_data_path);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+      break;
+  }
+}
+
+static void fl_dart_project_dispose(GObject* object) {
+  FlDartProject* self = FL_DART_PROJECT(object);
+
+  g_clear_pointer(&self->assets_path, g_free);
+  g_clear_pointer(&self->icu_data_path, g_free);
+
+  G_OBJECT_CLASS(fl_dart_project_parent_class)->dispose(object);
+}
+
+static void fl_dart_project_class_init(FlDartProjectClass* klass) {
+  G_OBJECT_CLASS(klass)->set_property = fl_dart_project_set_property;
+  G_OBJECT_CLASS(klass)->get_property = fl_dart_project_get_property;
+  G_OBJECT_CLASS(klass)->dispose = fl_dart_project_dispose;
+
+  g_object_class_install_property(
+      G_OBJECT_CLASS(klass), PROP_ASSETS_PATH,
+      g_param_spec_string(
+          "assets-path", "assets-path", "Path to Flutter assets", nullptr,
+          static_cast<GParamFlags>(G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
+                                   G_PARAM_STATIC_STRINGS)));
+  g_object_class_install_property(
+      G_OBJECT_CLASS(klass), PROP_ICU_DATA_PATH,
+      g_param_spec_string(
+          "icu-data-path", "icu-data-path", "Path to ICU data", nullptr,
+          static_cast<GParamFlags>(G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
+                                   G_PARAM_STATIC_STRINGS)));
+}
+
+static void fl_dart_project_init(FlDartProject* self) {}
+
+/**
+ * fl_dart_project_new:
+ * @assets_path: a file path, e.g. "build/assets"
+ * @icu_data_path: a file path, e.g. "build/icudtl.dat"
+ *
+ * Create a Flutter project.
+ *
+ * Returns: a new #FlDartProject
+ */
+G_MODULE_EXPORT FlDartProject* fl_dart_project_new(const gchar* assets_path,
+                                                   const gchar* icu_data_path) {
+  return static_cast<FlDartProject*>(
+      g_object_new(fl_dart_project_get_type(), "assets-path", assets_path,
+                   "icu-data-path", icu_data_path, nullptr));
+}
+
+/**
+ * fl_dart_project_get_assets_path:
+ * @view: a #FlDartProject
+ *
+ * Get the path to the directory containing the assets used in the Flutter
+ * application.
+ *
+ * Returns: a file path, e.g. "build/assets"
+ */
+G_MODULE_EXPORT const gchar* fl_dart_project_get_assets_path(
+    FlDartProject* self) {
+  g_return_val_if_fail(FL_IS_DART_PROJECT(self), nullptr);
+  return self->assets_path;
+}
+
+/**
+ * fl_dart_project_get_icu_data_path:
+ * @view: a #FlDartProject
+ *
+ * Get the path to the ICU data file in the Flutter application.
+ *
+ * Returns: a file path, e.g. "build/icudtl.dat"
+ */
+G_MODULE_EXPORT const gchar* fl_dart_project_get_icu_data_path(
+    FlDartProject* self) {
+  g_return_val_if_fail(FL_IS_DART_PROJECT(self), nullptr);
+  return self->icu_data_path;
+}