Implement window.alert() and its cousins for extensions.

BUG=12126
TEST=put a window.prompt() in a background page, a browser action, and a page action.
  Make sure it gets the result back correctly.  Also make sure it still works when
  called from a web page.
Review URL: http://codereview.chromium.org/341089

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31110 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 13 insertions, 9 deletions

diff --git a/chrome/browser/views/jsmessage_box_dialog.cc b/chrome/browser/views/jsmessage_box_dialog.cc
index 3fb70e0..b83242f 100644
--- a/chrome/browser/views/jsmessage_box_dialog.cc
+++ b/chrome/browser/views/jsmessage_box_dialog.cc
@@ -37,10 +37,15 @@ JavascriptMessageBoxDialog::~JavascriptMessageBoxDialog() {
 }
 
 void JavascriptMessageBoxDialog::ShowModalDialog() {
-  HWND root_hwnd = GetAncestor(tab_contents()->GetNativeView(),
-                               GA_ROOT);
-  dialog_ = views::Window::CreateChromeWindow(root_hwnd, gfx::Rect(), this);
-  dialog_->Show();
+  gfx::NativeWindow root_hwnd = client()->GetMessageBoxRootWindow();
+  // GetMessageBoxRootWindow() will be NULL if there's no selected tab (e.g.,
+  // during shutdown), in which case we simply skip showing this dialog.
+  if (!root_hwnd) {
+    Cancel();
+  } else {
+    dialog_ = views::Window::CreateChromeWindow(root_hwnd, gfx::Rect(), this);
+    dialog_->Show();
+  }
 }
 
 void JavascriptMessageBoxDialog::ActivateModalDialog() {
@@ -72,13 +77,12 @@ int JavascriptMessageBoxDialog::GetDialogButtons() const {
 }
 
 std::wstring JavascriptMessageBoxDialog::GetWindowTitle() const {
-  return parent_->title();;
+  return parent_->title();
 }
 
 
 void JavascriptMessageBoxDialog::WindowClosing() {
   dialog_ = NULL;
-
 }
 
 void JavascriptMessageBoxDialog::DeleteDelegate() {
diff --git a/chrome/browser/views/jsmessage_box_dialog.h b/chrome/browser/views/jsmessage_box_dialog.h
index f709a50..92a2635 100644
--- a/chrome/browser/views/jsmessage_box_dialog.h
+++ b/chrome/browser/views/jsmessage_box_dialog.h
@@ -11,7 +11,7 @@
 #include "views/window/dialog_delegate.h"
 
 class MessageBoxView;
-class TabContents;
+class JavaScriptMessageBoxClient;
 namespace views {
 class Window;
 }
@@ -47,8 +47,8 @@ class JavascriptMessageBoxDialog : public views::DialogDelegate {
   virtual void OnClose();
 
  private:
-  TabContents* tab_contents() {
-    return parent_->tab_contents();
+  JavaScriptMessageBoxClient* client() {
+    return parent_->client();
   }
 
   // A pointer to the AppModalDialog that owns us.