Notifications API support for images with multiple scale factors.

chrome/common/extensions/api/notifications.idl

Index: chrome/common/extensions/api/notifications.idl
diff --git a/chrome/common/extensions/api/notifications.idl b/chrome/common/extensions/api/notifications.idl
index da95e62c95a0c86116d435fe282fdccc2045521c..2060fd589d5fb31e64f8be4c2914163792d209c0 100644
--- a/chrome/common/extensions/api/notifications.idl
+++ b/chrome/common/extensions/api/notifications.idl
@@ -36,16 +36,27 @@ namespace notifications {
     DOMString message;
   };
 
-  [nodoc] dictionary NotificationBitmap {
-    long width;
-    long height;
-    ArrayBuffer? data;
+  // Contains an array of RGBA bitmap data, 32 bits per channel.  |data|
+  // should therefore have a length equal to 4 * width * height.
+  dictionary BitmapData {
+    ArrayBuffer data;
+    double width;
+    double height;
+  };
+
+  dictionary ImageRepresentation {
+    // The pixel ratio for which this bitmap is intended.
+    double scale;
+    // A URL from which the image will be downloaded.
+    (DOMString or BitmapData) data;
   };
 
   dictionary NotificationButton {
     DOMString title;
+    // The icon used with the button.  Either an icon URL or a spec must be
+    // provided.
     DOMString? iconUrl;
-    [nodoc] NotificationBitmap? iconBitmap;
+    ImageRepresentation[]? icons;

[benwells, 2014/06/27 03:15:27]

I think having these names be plural is confusing. There is only one icon being
provided but it is being produced with multiple representations.

Can we call it something like iconReps? Same goes for the notification options.

[dewittj, 2014/07/01 15:06:11]

Done.

   };
 
   dictionary NotificationOptions {
@@ -54,9 +65,9 @@ namespace notifications {
     TemplateType? type;
 
     // Sender's avatar, app icon, or a thumbnail for image notifications.

[benwells, 2014/06/27 03:15:27]

Are we intending notifications to have app icons here? I thought this would be
more notification specific, with the new app mask being how to communicate the
responsible app.

[dewittj, 2014/07/01 15:06:11]

We haven't been too prescriptive about what is acceptable in each area of the
UI, and I think that's a good thing.  When I've written apps for the
notification center, I frequently use people's images when available, but
generic icons if there isn't a more specific picture for this particular data. 
So probably we should leave this more generic but also publish a
google-style-guide similar to the Android one that has guidelines for app
developers.

See also http://developer.android.com/design/patterns/notifications.html

[benwells, 2014/07/02 03:11:11]

I was thinking about the comment here not the name. I agree we don't want to be
prescriptive, however it might make sense to give guidance in the documentation
about what we think best practices are.

E.g. we could say here that "ideally this is an image for this specific
notification, e.g. avatar or a thumbnail. If there is nothing suitable a generic
app image is acceptable." blah blah blah.

-    // <em>Required for $(ref:notifications.create)</em> method.
+    // Either an iconUrl or a ImageRepresentation must be provided.
     DOMString? iconUrl;
-    [nodoc] NotificationBitmap? iconBitmap;
+    ImageRepresentation[]? icons;
 
     // Title of the notification (e.g. sender name for email).
     // <em>Required for $(ref:notifications.create)</em> method.
@@ -80,12 +91,13 @@ namespace notifications {
     // Text and icons for up to two notification action buttons.
     NotificationButton[]? buttons;
 
-    // Secondary notification content.
-    [nodoc] DOMString? expandedMessage;
+    // Secondary notification content.  This field is deprecated and unused.
+    [deprecated] DOMString? expandedMessage;
 
-    // Image thumbnail for image-type notifications.
+    // Image thumbnail for image-type notifications.  Either an imageUrl or an imageSpec
+    // must be provided.
     DOMString? imageUrl;
-    [nodoc] NotificationBitmap? imageBitmap;
+    ImageRepresentation[]? images;
 
     // Items for multi-item notifications.
     NotificationItem[]? items;