Suppress JavaScript dialogs when a tab puts itself into fullscreen.

chrome/browser/background/background_contents.cc

Index: chrome/browser/background/background_contents.cc
diff --git a/chrome/browser/background/background_contents.cc b/chrome/browser/background/background_contents.cc
index 20e949071f3165423d75595544100d0e352a991a..077a9535e761ab59d5d6b378f812af21ad60939b 100644
--- a/chrome/browser/background/background_contents.cc
+++ b/chrome/browser/background/background_contents.cc
@@ -123,7 +123,8 @@ void BackgroundContents::CloseContents(WebContents* source) {
   delete this;
 }
 
-bool BackgroundContents::ShouldSuppressDialogs(WebContents* source) {
+bool BackgroundContents::ShouldSuppressDialogs(WebContents* source,
+                                               bool before_unload) {
   return true;
 }