Forward MIME types to BrowserPlugin when a viewer is specified.

chrome/common/extensions/api/streams_private.idl

 // Copyright 2014 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.
 
 // Streams Private API.
 namespace streamsPrivate {
   dictionary StreamInfo {
     // The MIME type of the intercepted URL request.
     DOMString mimeType;
 
     // The original URL that was intercepted.
     DOMString originalUrl;
 
     // The URL that the stream can be read from.
     DOMString streamUrl;
 
-    // The ID of the tab that opened the stream. If the stream is not opened in
-    // a tab, it will be -1.
-    long tabId;
+    // The ID of the tab that opened the stream.

[not at google - send to devlin, 2014/04/30 15:42:43]

"Either/exactly-one-of |tabId| or |viewId| will be specified."?

[Zachary Kuznia, 2014/05/01 00:38:22]

Reverted this to old language and behavior.

+    long? tabId;
+
+    // The ID of the view that will render the stream.

[not at google - send to devlin, 2014/04/30 15:42:43]

ditto

[Zachary Kuznia, 2014/05/01 00:38:22]

Clarified the conditions where this will be set.

+    DOMString? viewId;
 
     // The amount of data the Stream should contain, if known.  If there is no
     // information on the size it will be -1.
     long expectedContentSize;
 
     // 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 ", ".
     object responseHeaders;
   };
 
   interface Events {
     // Fired when a resource is fetched which matches a mime type handled by
     // this extension. The resource request is cancelled, and the extension is
     // expected to handle the request. The event is restricted to a small number
     // of white-listed extensions.
     static void onExecuteMimeTypeHandler(StreamInfo streamInfo);
   };
 };