Disable use of occlusion APIs while bugs are fixed

content/browser/web_contents/web_contents_view_mac.mm

Index: content/browser/web_contents/web_contents_view_mac.mm
diff --git a/content/browser/web_contents/web_contents_view_mac.mm b/content/browser/web_contents/web_contents_view_mac.mm
index 20c97b8fda21f15ca37dbfccc2c575e172505fdf..3c99ac330ccad104477afa145c0cfdc8dba9fa52 100644
--- a/content/browser/web_contents/web_contents_view_mac.mm
+++ b/content/browser/web_contents/web_contents_view_mac.mm
@@ -605,6 +605,12 @@ void WebContentsViewMac::CloseTab() {
   // Occlusion notification APIs are new in Mavericks.
   bool supportsOcclusionAPIs = base::mac::IsOSMavericksOrLater();
 
+  // Use of occlusion APIs is causing bugs:
+  // http://crbug.com/430968: focus set incorrectly.
+  // http://crbug.com/431272: flashes of incorrect content.
+  // http://crbug.com/310374: white flashes (comment 22).
+  supportsOcclusionAPIs = false;
+
   if (supportsOcclusionAPIs) {
     if (oldWindow) {
       [notificationCenter