add docs

docs/api/download-item.md

@@ -146,3 +146,23 @@ header.
 #### `downloadItem.getState()`
 
 Returns `String` - The current state.  Can be `progressing`, `completed`, `cancelled` or `interrupted`.
+
+**Note:** The following methods are useful specifically to resume a
+`cancelled` item when session is restarted.
+
+#### `downloadItem.getURLChain()`
+
+Returns `String[]` - The complete url chain of the item including any redirects.
+
+#### `downloadItem.getLastModifiedTime()`
+
+Returns `String` - Last-Modified header value.
+
+#### `downloadItem.getETag()`
+
+Returns `String` - ETag header value.
+
+#### `downloadItem.getStartTime()`
+
+Returns `Double` - Number of seconds since the UNIX epoch when the download was
+started.

docs/api/session.md

@@ -344,6 +344,25 @@ Returns `String` - The user agent for this session.
 
 Returns `Blob` - The blob data associated with the `identifier`.
 
+#### `ses.createInterruptedDownload(options)`
+
+* `options` Object
+  * `path` String - Absolute path of the download.
+  * `urlChain` String[] - Complete URL chain for the download.
+  * `mimeType` String (optional)
+  * `offset` Integer - Start range for the download.
+  * `length` Integer - Total length of the download.
+  * `lastModified` String - Last-Modified header value.
+  * `eTag` String - ETag header value.
+  * `startTime` Double (optional) - Time when download was started in
+    number of seconds since UNIX epoch.
+
+Allows resuming `cancelled` or `interrupted` downloads from previous `Session`.
+The API will generate a [DownloadItem](download-item.md) that can be accessed with the [will-download](#event-will-download)
+event. The [DownloadItem](download-item.md) will not have any `WebContents` associated with it and
+the initial state will be `interrupted`. The download will start only when the
+`resume` API is called on the [DownloadItem](download-item.md).
+
 ### Instance Properties
 
 The following properties are available on instances of `Session`: