Mozart: Specify texture origin explicitly.

mojo/services/gfx/composition/interfaces/resources.mojom

Index: mojo/services/gfx/composition/interfaces/resources.mojom
diff --git a/mojo/services/gfx/composition/interfaces/resources.mojom b/mojo/services/gfx/composition/interfaces/resources.mojom
index f2f9a525d5567f27ae0bd8cca9301d6410b5672e..71c73eba5234f414fbd0c3cd0a45f30ce5becf6d 100644
--- a/mojo/services/gfx/composition/interfaces/resources.mojom
+++ b/mojo/services/gfx/composition/interfaces/resources.mojom
@@ -37,6 +37,12 @@ struct SceneResource {
 //
 // TODO(jeffbrown): Replace this with Image and ImagePipe.
 struct MailboxTextureResource {
+  // The origin of the texture.
+  enum Origin {
+    TOP_LEFT,
+    BOTTOM_LEFT,
+  };
+
   // The name of the mailbox, as produced by glGenMailboxCHROMIUM().
   array<uint8, 64> mailbox_name;
 
@@ -47,6 +53,9 @@ struct MailboxTextureResource {
   // The size of the texture in pixels.
   mojo.Size size;
 
+  // The origin of the texture.
+  Origin origin = Origin.TOP_LEFT;
+
   // The callback interface to be notified when it is safe to release or
   // recycle the underlying texture storage once the resource has been
   // removed from the scene.