osr_test: extend accessibility location-change grace period to 3 s

Python 3.14 is slow enough that the previous 1 s unconditional extra
wait was still insufficient for the OnAccessibilityLocationChange IPC
to arrive before check_auto_asserts ran.

Replace the single fixed-length wait with a polling loop: up to 30
batches of 10 iterations (100 ms each) = 3 s maximum, but exits
immediately once the flag is set.  Fast runners (3.10-3.13) continue
to pay nothing extra; 3.14 gets as much time as it needs up to 3 s.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: linesight

unittests/osr_test.py

@@ -186,10 +186,14 @@ def test_osr(self):
         run_message_loop()
 
         # OnAccessibilityLocationChange arrives via a separate renderer IPC and
-        # can lag behind OnAccessibilityTreeChange on slow CI runners.  Give it
-        # up to 1 extra second before closing the browser.
-        if not accessibility_handler._OnAccessibilityLocationChange_True:
-            do_message_loop_work(100)
+        # can lag behind OnAccessibilityTreeChange on slow CI runners (e.g.
+        # Python 3.14 adds enough overhead that 1 s was insufficient).
+        # Poll in 100 ms batches, up to 3 extra seconds, and exit as soon as
+        # the flag is set so fast runners pay nothing extra.
+        for _ in range(30):
+            if accessibility_handler._OnAccessibilityLocationChange_True:
+                break
+            do_message_loop_work(10)
 
         # Close browser and clean reference
         browser.CloseBrowser(True)