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 33c549cdfb4d5dbdc07be36fbdaa0099289890fb..97f74297c305b2e90c9caed6d1c08a4a08d4775e 100644
--- a/chrome/browser/chromeos/login/webui_login_view.cc
+++ b/chrome/browser/chromeos/login/webui_login_view.cc
@@ -5,6 +5,8 @@
 #include "chrome/browser/chromeos/login/webui_login_view.h"
 
 #include "base/i18n/rtl.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"
@@ -15,6 +17,8 @@
 #include "chrome/browser/chromeos/wm_ipc.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/views/dom_view.h"
+#include "chrome/common/render_messages.h"
+#include "content/browser/renderer_host/render_view_host_observer.h"
 #include "content/browser/tab_contents/tab_contents.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
@@ -33,6 +37,39 @@ 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 ChromeViewMsg_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(ChromeViewHostMsg_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_;
+};
+
 // A View class which places its first child at the right most position.
 class RightAlignedView : public views::View {
  public:
@@ -53,7 +90,6 @@ void RightAlignedView::ChildPreferredSizeChanged(View* child) {
   Layout();
 }
 
-
 }  // namespace
 
 namespace chromeos {
@@ -226,6 +262,10 @@ void WebUILoginView::OnLocaleChanged() {
   SchedulePaint();
 }
 
+void WebUILoginView::OnRenderHostCreated(RenderViewHost* host) {
+  new SnifferObserver(host, GetWebUI());
+}
+
 void WebUILoginView::OnTabMainFrameLoaded() {
 }