Suppress JavaScript dialogs when a tab puts itself into fullscreen.

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index 39519544c8df67a06252595604997d394b10d618..32c9ddd2673877e188fc50b7efc58c1d2e91652c 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -1206,6 +1206,16 @@ bool Browser::CanOverscrollContent() const {
   return true;
 }
 
+bool Browser::ShouldSuppressDialogs(WebContents* source, bool before_unload) {
+  if (before_unload)
+    return false;
+
+  // In the case where fullscreen was triggered by the web page ("tab
+  // fullscreen"), do not allow dialogs. This does not affect the case of user-
+  // initiated fullscreen ("browser fullscreen").
+  return exclusive_access_manager_->fullscreen_controller()->IsTabFullscreen();
+}
+
 bool Browser::ShouldPreserveAbortedURLs(WebContents* source) {
   // Allow failed URLs to stick around in the omnibox on the NTP, but not when
   // other pages have committed.