Add a mimeHandler extension API.

extensions/common/api/mime_handler.mojom

+// Copyright 2015 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.
+
+module extensions.mime_handler;
+
+// Information about a stream.
+struct StreamInfo {
+  // The MIME type of the intercepted URL request.
+  string mime_type;
+
+  // The original URL that was intercepted.
+  string original_url;
+
+  // The URL that the stream can be read from.
+  string stream_url;
+
+  // The ID of the tab that opened the stream. If the stream is not opened in a
+  // tab, it will be -1.
+  int32 tab_id;
+
+  // The amount of data the Stream should contain, if known. If there is no
+  // information on the size it will be -1.
+  int64 expected_content_size;
+
+  // The HTTP response headers of the intercepted request stored as a dictionary
+  // mapping header name to header value. If a header name appears multiple
+  // times, the header values are merged in the dictionary and separated by a ",

[raymes, 2015/01/12 05:26:04]

nit: maybe push " onto the next line

[Sam McNally, 2015/01/12 07:13:35]

Done.

+  // ".
+  map<string, string> response_headers;
+
+  // Whether the stream is embedded within another document.
+  bool embedded;
+};
+
+interface MimeHandlerService {
+  // Returns information about the stream associated with this service instance.
+  // If the stream has been aborted, |stream_info| will be null.
+  GetStreamInfo() => (StreamInfo? stream_info);
+
+  // Aborts the stream associated with this service instance. This is an
+  // idempotent operation.
+  AbortStream() => ();

[raymes, 2015/01/12 05:26:04]

Maybe we should have a callback for this so we can test better :)

[Sam McNally, 2015/01/12 07:13:35]

It does have a callback. It just didn't bother waiting for the stream to
actually close.

+};