Add MinidumpMemoryListWriter::AddFromSnapshot(), everything downstream and its test

snapshot/test/test_memory_snapshot.cc

Index: snapshot/test/test_memory_snapshot.cc
diff --git a/snapshot/test/test_memory_snapshot.cc b/snapshot/test/test_memory_snapshot.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5201be06fa3c68737061c675a5f494c16534d891
--- /dev/null
+++ b/snapshot/test/test_memory_snapshot.cc
@@ -0,0 +1,47 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "snapshot/test/test_memory_snapshot.h"
+
+#include <string>
+
+namespace crashpad {
+namespace test {
+
+TestMemorySnapshot::TestMemorySnapshot()
+    : address_(0), size_(0), value_('\0') {
+}
+
+TestMemorySnapshot::~TestMemorySnapshot() {
+}
+
+uint64_t TestMemorySnapshot::Address() const {
+  return address_;
+}
+
+size_t TestMemorySnapshot::Size() const {
+  return size_;
+}
+
+bool TestMemorySnapshot::Read(Delegate* delegate) const {
+  if (size_ == 0) {
+    return delegate->MemorySnapshotDelegateRead(nullptr, size_);
+  }
+
+  std::string buffer(size_, value_);
+  return delegate->MemorySnapshotDelegateRead(&buffer[0], size_);
+}
+
+}  // namespace test
+}  // namespace crashpad