Fix macOS ARM OSR: exclude disable-surfaces/begin-frame switches, extend init timeout

On macOS ARM, the viz Surfaces API is required for OSR browser creation.
--disable-surfaces (and its companion --enable-begin-frame-scheduling) prevent
viz from initialising, causing CefBrowserHost::CreateBrowserSync() to return
null.  Exclude both switches on macOS so the Surfaces pipeline stays alive.

Also extend the OnContextInitialized pump loop from 6 s to 30 s to give slower
CI environments enough time before CreateBrowserSync() falls back to the
deferred (None-returning) path.

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

Author: linesight

src/cefpython.pyx

@@ -622,18 +622,18 @@ def Initialize(applicationSettings=None, commandLineSwitches=None, **kwargs):
     # guarantees that CreateBrowserSync() can be called immediately after
     # Initialize() without hitting the deferred-creation path or getting
     # a null browser from CefBrowserHost::CreateBrowserSync().
-    # 200 * 10ms = 2 seconds max; OnContextInitialized typically fires
-    # within the first few iterations.
+    # OnContextInitialized typically fires within the first few iterations;
+    # allow up to 30 seconds for slow CI environments.
     if ret:
-        for _ in range(600):
+        for _ in range(3000):
             with nogil:
                 CefDoMessageLoopWork()
             if g_context_initialized:
                 break
             time.sleep(0.01)
         if not g_context_initialized:
             Debug("CefInitialize() WARNING: OnContextInitialized not received"
-                  " within 6 seconds")
+                  " within 30 seconds")
 
     if sys.platform.startswith("linux"):
         # Install by default.

unittests/osr_test.py

@@ -107,11 +107,13 @@ def test_osr(self):
             # it using these Chromium switches (Issue #240 and #463)
             "disable-gpu": "",
             "disable-gpu-compositing": "",
-            # Tweaking OSR performance by setting the same Chromium flags
-            # as in upstream cefclient (Issue #240).
-            "enable-begin-frame-scheduling": "",
-            "disable-surfaces": "",  # This is required for PDF ext to work
         }
+        if not MAC:
+            # Tweaking OSR performance (Issue #240). On macOS ARM the viz
+            # Surfaces API is required for OSR browser creation, so these
+            # switches (which disable it) must not be passed there.
+            switches["enable-begin-frame-scheduling"] = ""
+            switches["disable-surfaces"] = ""  # Required for PDF ext to work
         if LINUX:
             # Sandbox setup fails on CI runners.
             switches["no-sandbox"] = ""