Re-land "view permission" feature (r179916) with Mac Fix.

chrome/browser/ui/views/extensions/extension_install_dialog_view.cc

Index: chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
diff --git a/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc b/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
index 877b0e3a8f43cf4b6a0a4696802e86edb3686059..f9aa70d6a4ed2038d0619b24d9870be2a0c7c853 100644
--- a/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
+++ b/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
@@ -95,6 +95,7 @@ class ExtensionInstallDialogView : public views::DialogDelegateView,
 
  private:
   // views::DialogDelegateView:
+  virtual int GetDialogButtons() const OVERRIDE;
   virtual string16 GetDialogButtonLabel(ui::DialogButton button) const OVERRIDE;
   virtual int GetDefaultDialogButton() const OVERRIDE;
   virtual bool Cancel() OVERRIDE;
@@ -443,6 +444,14 @@ void ExtensionInstallDialogView::SizeToContents() {
   GetWidget()->SetSize(GetWidget()->non_client_view()->GetPreferredSize());
 }
 
+int ExtensionInstallDialogView::GetDialogButtons() const {
+  int buttons = prompt_.GetDialogButtons();
+  // Simply having just an OK button is *not* supported. See comment on function
+  // GetDialogButtons in dialog_delegate.h for reasons.
+  DCHECK_GT(buttons & ui::DIALOG_BUTTON_CANCEL, 0);
+  return buttons;
+}
+
 string16 ExtensionInstallDialogView::GetDialogButtonLabel(
     ui::DialogButton button) const {
   switch (button) {