UIA: Fix Win7 test failure

Win7 builds weren't being regularly run when CL:1510772 was merged, so
a Win7 failure was introduced.

Since UIA_LiveSettingPropertyId does not exist on Win7 (introduced in
Win8), the test-expectation file for the `live-region-create` test
needs to be split; Win10 will receive a change notification, but Win7
won't.

Since this is currently the only expected event from that test, the Win7
file introduced here is empty.

Bug: 928949
Change-Id: I7f1518387dcc75c90172d525d30965b0ba4e9ec4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1535343
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Ian Prest <iapres@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#643292}
diff --git a/content/test/data/accessibility/event/live-region-create-expected-uia-win7.txt b/content/test/data/accessibility/event/live-region-create-expected-uia-win7.txt
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/content/test/data/accessibility/event/live-region-create-expected-uia-win7.txt