Port touch-demo.sky to Dart and make it work in SkyShell

sky/shell/platform_view.cc

Index: sky/shell/platform_view.cc
diff --git a/sky/shell/platform_view.cc b/sky/shell/platform_view.cc
index e31498dcb39722b110723b8b354f9f0329b0960b..69a7b10a1c130ca00e18b43430d5b509e5cf0fd9 100644
--- a/sky/shell/platform_view.cc
+++ b/sky/shell/platform_view.cc
@@ -16,8 +16,12 @@
 namespace sky {
 namespace shell {
 
-static jlong Attach(JNIEnv* env, jclass clazz) {
-  return reinterpret_cast<jlong>(Shell::Shared().view());
+static jlong Attach(JNIEnv* env, jclass clazz, jint viewportObserverHandle) {
+  PlatformView* view = Shell::Shared().view();
+  view->ConnectToViewportObserver(
+      mojo::MakeRequest<ViewportObserver>(mojo::ScopedMessagePipeHandle(
+          mojo::MessagePipeHandle(viewportObserverHandle))));
+  return reinterpret_cast<jlong>(view);
 }
 
 // static
@@ -34,6 +38,14 @@ PlatformView::~PlatformView() {
     ReleaseWindow();
 }
 
+void PlatformView::ConnectToViewportObserver(
+    mojo::InterfaceRequest<ViewportObserver> request) {
+  config_.ui_task_runner->PostTask(
+      FROM_HERE,
+      base::Bind(&UIDelegate::ConnectToViewportObserver, config_.ui_delegate,
+                 base::Passed(&request)));
+}
+
 void PlatformView::Detach(JNIEnv* env, jobject obj) {
   DCHECK(!window_);
 }
@@ -60,17 +72,6 @@ void PlatformView::SurfaceDestroyed(JNIEnv* env, jobject obj) {
   ReleaseWindow();
 }
 
-void PlatformView::SurfaceSetSize(JNIEnv* env,
-                                  jobject obj,
-                                  jint width,
-                                  jint height,
-                                  jfloat density) {
-  config_.ui_task_runner->PostTask(
-      FROM_HERE,
-      base::Bind(&UIDelegate::OnViewportMetricsChanged, config_.ui_delegate,
-                 gfx::Size(width, height), density));
-}
-
 void PlatformView::ReleaseWindow() {
   ANativeWindow_release(window_);
   window_ = nullptr;