Mozart: Enhance tile app to test various sync behaviors.

By passing URL arguments, tile can now be made to construct its
scene using different version modes, combinator modes, or orientations.
Note that the "views=" key must now be used to specify the set of
view URLs.  See README for details.

BUG=
R=abarth@google.com

Review URL: https://codereview.chromium.org/1869263002 .

examples/ui/tile/README.md

diff --git a/examples/ui/tile/README.md b/examples/ui/tile/README.md
index 86ec7a8..4d05618 100644
--- a/examples/ui/tile/README.md
+++ b/examples/ui/tile/README.md
@@ -8,8 +8,31 @@
 
 ## USAGE
 
-  out/Debug/mojo_shell "mojo:launcher mojo:tile_view?<app1>[,<app2>[,...]]"
+Specify the urls of the views to embed as a comma-delimited query string.
 
-Specify the urls of the views to embed as a comma-delimited query parameter.
+  out/Debug/mojo_shell "mojo:launcher mojo:tile_view?views=<app1>[,<app2>[,...]]"
 
-  eg. out/Debug/mojo_shell "mojo:launcher mojo:tile_view?mojo:spinning_cube_view,mojo:noodles_view"
+  eg. out/Debug/mojo_shell "mojo:launcher mojo:tile_view?views=mojo:spinning_cube_view,mojo:noodles_view"
+
+The query string may also encode tiling options by appending parameters to
+the end of the query string.
+
+  Version mode for child views:
+
+    &vm=any   : composite most recent unblocked version of each child (default)
+    &vm=exact : composite only exact version of child specified during
+                layout (forces frame-level synchronization of resizing)
+
+  Combinator mode for child views:
+
+    &cm=merge : use MERGE combinator (default)
+    &cm=prune : use PRUNE combinator
+    &cm=flash : use FALLBACK combinator with solid red color as
+                alternate content
+    &cm=dim   : use FALLBACK combinator with a dimmed layer containing the
+                most recent unblocked version of the child
+
+  Orientation mode for child views:
+
+    &o=h : tile children horizontally
+    &o=v : tile children vertically