Fix browser launch on the login screen.

For the login screen, if there is some web content displayed, and the user clicks a link that is specified to open in a new window, a new browser window indeed opens, which is highly undesirable at the login screen.
To avoid this, a new delegate method was introduced, which should decide if we want to allow displaying any additional contents.

BUG=443096
TEST=manual

Review URL: https://codereview.chromium.org/812763003

Cr-Commit-Position: refs/heads/master@{#314311}

chrome/browser/chromeos/login/ui/login_web_dialog.cc

@@ -10,6 +10,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chromeos/login/helper.h"
 #include "chrome/browser/ui/browser_dialogs.h"
+#include "chrome/browser/ui/browser_finder.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
@@ -157,6 +158,23 @@ bool LoginWebDialog::HandleContextMenu(
   return true;
 }
 
+bool LoginWebDialog::HandleOpenURLFromTab(
+    content::WebContents* source,
+    const content::OpenURLParams& params,
+    content::WebContents** out_new_contents) {
+  // On a login screen, if a missing extension is trying to show in a web
+  // dialog, a NetErrorHelper is displayed instead (hence we have a |source|),
+  // but there is no browser window associated with it. A helper screen will
+  // fire an auto-reload, which in turn leads to opening a new browser window,
+  // so we must suppress it.
+  // http://crbug.com/443096
+  return (source && !chrome::FindBrowserWithWebContents(source));
+}
+
+bool LoginWebDialog::HandleShouldCreateWebContents() {
+  return false;
+}
+
 void LoginWebDialog::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {

chrome/browser/chromeos/login/ui/login_web_dialog.h

@@ -81,6 +81,10 @@ class LoginWebDialog : public ui::WebDialogDelegate,
                        bool* out_close_dialog) override;
   bool ShouldShowDialogTitle() const override;
   bool HandleContextMenu(const content::ContextMenuParams& params) override;
+  bool HandleOpenURLFromTab(content::WebContents* source,
+                            const content::OpenURLParams& params,
+                            content::WebContents** out_new_contents) override;
+  bool HandleShouldCreateWebContents() override;
 
   // content::NotificationObserver implementation.
   void Observe(int type,

ui/views/controls/webview/web_dialog_view.cc

@@ -331,6 +331,20 @@ void WebDialogView::BeforeUnloadFired(content::WebContents* tab,
   *proceed_to_fire_unload = proceed;
 }
 
+bool WebDialogView::ShouldCreateWebContents(
+    content::WebContents* web_contents,
+    int route_id,
+    int main_frame_route_id,
+    WindowContainerType window_container_type,
+    const base::string16& frame_name,
+    const GURL& target_url,
+    const std::string& partition_id,
+    content::SessionStorageNamespace* session_storage_namespace) {
+  if (delegate_)
+    return delegate_->HandleShouldCreateWebContents();
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // WebDialogView, private:
 

ui/views/controls/webview/web_dialog_view.h

@@ -111,6 +111,15 @@ class WEBVIEW_EXPORT WebDialogView : public views::ClientView,
   void BeforeUnloadFired(content::WebContents* tab,
                          bool proceed,
                          bool* proceed_to_fire_unload) override;
+  bool ShouldCreateWebContents(
+      content::WebContents* web_contents,
+      int route_id,
+      int main_frame_route_id,
+      WindowContainerType window_container_type,
+      const base::string16& frame_name,
+      const GURL& target_url,
+      const std::string& partition_id,
+      content::SessionStorageNamespace* session_storage_namespace) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(WebDialogBrowserTest, WebContentRendered);

ui/web_dialogs/web_dialog_delegate.cc

@@ -48,4 +48,8 @@ bool WebDialogDelegate::HandleAddNewContents(
   return false;
 }
 
+bool WebDialogDelegate::HandleShouldCreateWebContents() {
+  return true;
+}
+
 }  // namespace ui

ui/web_dialogs/web_dialog_delegate.h

@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/strings/string16.h"
+#include "content/public/browser/web_contents_delegate.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/base/window_open_disposition.h"
 #include "ui/web_dialogs/web_dialogs_export.h"
@@ -128,6 +129,10 @@ class WEB_DIALOGS_EXPORT WebDialogDelegate {
                                     const gfx::Rect& initial_pos,
                                     bool user_gesture);
 
+  // A callback to control whether a WebContents will be created. Returns
+  // false to disallow the creation. Return true to use the default handler.
+  virtual bool HandleShouldCreateWebContents();
+
   // Stores the dialog bounds.
   virtual void StoreDialogSize(const gfx::Size& dialog_size) {}