Only allow to lock the mouse when the tab is in fullscreen mode.

content/browser/tab_contents/tab_contents_delegate.cc

Index: content/browser/tab_contents/tab_contents_delegate.cc
diff --git a/content/browser/tab_contents/tab_contents_delegate.cc b/content/browser/tab_contents/tab_contents_delegate.cc
index 6877f7955199c9086dcc0153b07f3d177c805be2..10ae5f4629382f6125274bee674d97e1f97eb8f7 100644
--- a/content/browser/tab_contents/tab_contents_delegate.cc
+++ b/content/browser/tab_contents/tab_contents_delegate.cc
@@ -294,6 +294,10 @@ void TabContentsDelegate::ToggleFullscreenModeForTab(TabContents* tab,
                                                      bool enter_fullscreen) {
 }
 
+bool TabContentsDelegate::IsFullscreenForTab(const TabContents* tab) const {
+  return false;
+}
+
 void TabContentsDelegate::JSOutOfMemory(TabContents* tab) {
 }