media: Add MemoryDataSource.

media/filters/memory_data_source.cc

Index: media/filters/memory_data_source.cc
diff --git a/media/filters/memory_data_source.cc b/media/filters/memory_data_source.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d38803ee702e2d1a017b5f7c3e57d54495f34d7e
--- /dev/null
+++ b/media/filters/memory_data_source.cc
@@ -0,0 +1,57 @@
+// Copyright 2016 The Chromium 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 "media/filters/memory_data_source.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+
+namespace media {
+
+MemoryDataSource::MemoryDataSource(const uint8_t* data, size_t size)
+    : data_(data), size_(size) {}
+
+MemoryDataSource::~MemoryDataSource() {}
+
+void MemoryDataSource::Read(int64_t position,
+                            int size,
+                            uint8_t* data,
+                            const DataSource::ReadCB& read_cb) {
+  DCHECK(!read_cb.is_null());
+
+  if (is_stopped_ || size < 0 || position < 0 ||
+      static_cast<size_t>(position) > size_) {
+    read_cb.Run(kReadError);
+    return;
+  }
+
+  // Cap size within bounds.
+  size_t clamped_size = std::min(static_cast<size_t>(size),
+                                 size_ - static_cast<size_t>(position));
+
+  if (clamped_size > 0) {
+    DCHECK(data);
+    memcpy(data, data_ + position, clamped_size);
+  }
+
+  read_cb.Run(clamped_size);
+}
+
+void MemoryDataSource::Stop() {
+  is_stopped_ = true;
+}
+
+bool MemoryDataSource::GetSize(int64_t* size_out) {
+  *size_out = size_;
+  return true;
+}
+
+bool MemoryDataSource::IsStreaming() {
+  return false;
+}
+
+void MemoryDataSource::SetBitrate(int bitrate) {}
+
+}  // namespace media