Improve performance of Dart_ListGetAsBytes.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
===================================================================
--- runtime/vm/dart_api_impl_test.cc	(revision 25704)
+++ runtime/vm/dart_api_impl_test.cc	(working copy)
@@ -832,6 +832,39 @@
 }
 
 
+TEST_CASE(TypedDataViewListGetAsBytes) {
+  const int kSize = 1000;
+
+  const char* kScriptChars =
+      "import 'dart:typed_data';\n"
+      "List main(int size) {\n"
+      "  var a = new Int8List(size);\n"
+      "  var view = new Int8List.view(a.buffer, 0, size);\n"
+      "  return view;\n"
+      "}\n";
+  // Create a test library and Load up a test script in it.
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
+
+  // Test with a typed data view object.
+  Dart_Handle dart_args[1];
+  dart_args[0] = Dart_NewInteger(kSize);
+  Dart_Handle view_obj = Dart_Invoke(lib, NewString("main"), 1, dart_args);
+  EXPECT_VALID(view_obj);
+  for (intptr_t i = 0; i < kSize; ++i) {
+    EXPECT_VALID(Dart_ListSetAt(view_obj, i, Dart_NewInteger(i & 0xff)));
+  }
+  uint8_t* data = new uint8_t[kSize];
+  EXPECT_VALID(Dart_ListGetAsBytes(view_obj, 0, data, kSize));
+  for (intptr_t i = 0; i < kSize; ++i) {
+    EXPECT_EQ(i & 0xff, data[i]);
+  }
+
+  Dart_Handle result = Dart_ListGetAsBytes(view_obj, 0, data, kSize + 1);
+  EXPECT(Dart_IsError(result));
+  delete[] data;
+}
+
+
 TEST_CASE(TypedDataAccess) {
   EXPECT_EQ(Dart_TypedData_kInvalid,
             Dart_GetTypeOfTypedData(Dart_True()));