Disable window occlusion APIs when running browser tests

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 1dac476d35e878ef2f8f2aa41cf17f43688ec4cd..4247674fc9dd05ec55bb281d453478803f518985 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -90,6 +90,11 @@ const char kDisableAcceleratedVideoDecode[] =
 // users with many windows/tabs and lots of memory.
 const char kDisableBackingStoreLimit[]      = "disable-backing-store-limit";
 
+// Disable backgrounding renders for occluded windows. Done for tests to avoid
+// nondeterministic behavior.
+extern const char kDisableBackgroundingOccludedWindows[] =
+    "disable-backgrounding-occluded-windows";
+
 // Disable one or more Blink runtime-enabled features.
 // Use names from RuntimeEnabledFeatures.in, separated by commas.
 // Applied after kEnableBlinkFeatures, and after other flags that change these