Implements frame sniffer to watch iframe loading state.

chrome/browser/chromeos/login/webui_login_view.cc

Index: chrome/browser/chromeos/login/webui_login_view.cc
diff --git a/chrome/browser/chromeos/login/webui_login_view.cc b/chrome/browser/chromeos/login/webui_login_view.cc
index 6445ea63b92eeadd69511c404af590b690ab6ca1..0fa0ffb5e02d2fa515325e349dc2f21cadf1ef13 100644
--- a/chrome/browser/chromeos/login/webui_login_view.cc
+++ b/chrome/browser/chromeos/login/webui_login_view.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/chromeos/login/webui_login_view.h"
 
+#include "base/utf_string_conversions.h"
+#include "base/values.h"
 #include "chrome/browser/chromeos/accessibility_util.h"
 #include "chrome/browser/chromeos/login/proxy_settings_dialog.h"
 #include "chrome/browser/chromeos/login/webui_login_display.h"
@@ -14,7 +16,9 @@
 #include "chrome/browser/chromeos/wm_ipc.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/views/dom_view.h"
+#include "content/browser/renderer_host/render_view_host_observer.h"
 #include "content/browser/tab_contents/tab_contents.h"
+#include "content/common/view_messages.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 #include "views/widget/native_widget_gtk.h"
@@ -32,6 +36,39 @@ const char kViewClassName[] = "browser/chromeos/login/WebUILoginView";
 const char kAccelNameAccessibility[] = "accessibility";
 const char kAccelNameEnrollment[] = "enrollment";
 
+// Observes IPC messages from the FrameSniffer and notifies JS if error
+// appears.
+class SnifferObserver : public RenderViewHostObserver {
+ public:
+  SnifferObserver(RenderViewHost* host, WebUI* webui)
+      : RenderViewHostObserver(host), webui_(webui) {
+    DCHECK(webui_);
+    Send(new ViewMsg_StartFrameSniffer(routing_id(),
+                                       UTF8ToUTF16("gaia-frame")));
+  }
+
+  virtual ~SnifferObserver() {}
+
+  // IPC::Channel::Listener implementation.
+  virtual bool OnMessageReceived(const IPC::Message& message) {
+    bool handled = true;
+    IPC_BEGIN_MESSAGE_MAP(SnifferObserver, message)
+      IPC_MESSAGE_HANDLER(ViewHostMsg_FrameLoadingError, OnError)
+      IPC_MESSAGE_UNHANDLED(handled = false)
+    IPC_END_MESSAGE_MAP()
+    return handled;
+  }
+
+ private:
+  void OnError(int error) {
+    base::FundamentalValue error_value(error);
+    webui_->CallJavascriptFunction("login.OfflineMessageScreen.onFrameError",
+                                   error_value);
+  }
+
+  WebUI* webui_;
+};
+
 }  // namespace
 
 namespace chromeos {
@@ -204,6 +241,10 @@ void WebUILoginView::OnLocaleChanged() {
   SchedulePaint();
 }
 
+void WebUILoginView::OnRenderHostCreated(RenderViewHost* host) {
+  new SnifferObserver(host, GetWebUI());
+}
+
 void WebUILoginView::OnTabMainFrameLoaded() {
 }