Grab inputs on WebUI screen locker.

chrome/browser/chromeos/login/webui_screen_locker.cc

Index: chrome/browser/chromeos/login/webui_screen_locker.cc
diff --git a/chrome/browser/chromeos/login/webui_screen_locker.cc b/chrome/browser/chromeos/login/webui_screen_locker.cc
index 6b64dc5afe73556e9648540b0a87d4a39fcb1e61..8a253499208a4369e8eda6e7114d795683904ab8 100644
--- a/chrome/browser/chromeos/login/webui_screen_locker.cc
+++ b/chrome/browser/chromeos/login/webui_screen_locker.cc
@@ -23,9 +23,11 @@
 #include "chrome/browser/chromeos/login/screen_locker.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/chromeos/login/webui_login_display.h"
+#include "chrome/browser/ui/views/dom_view.h"
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/url_constants.h"
+#include "content/browser/renderer_host/render_widget_host_view.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "ui/base/l10n/l10n_util.h"
@@ -38,27 +40,29 @@ namespace {
 // URL which corresponds to the login WebUI.
 const char kLoginURL[] = "chrome://oobe/login";
 
+// The maximum duration for which locker should try to grab the keyboard and
+// mouse and its interval for regrabbing on failure.
+const int kMaxGrabFailureSec = 30;
+const int64 kRetryGrabIntervalMs = 500;
+
+// Maximum number of times we'll try to grab the keyboard and mouse before
+// giving up.  If we hit the limit, Chrome exits and the session is terminated.
+const int kMaxGrabFailures = kMaxGrabFailureSec * 1000 / kRetryGrabIntervalMs;
+
 // A ScreenLock window that covers entire screen to keep the keyboard
 // focus/events inside the grab widget.
 class LockWindow : public views::NativeWidgetGtk {
  public:
-  LockWindow()
+  explicit LockWindow(chromeos::WebUIScreenLocker* webui_screen_locker)
       : views::NativeWidgetGtk(new views::Widget),
-        toplevel_focus_widget_(NULL) {
+        toplevel_focus_widget_(NULL),
+        webui_screen_locker_(webui_screen_locker) {
     EnableDoubleBuffer(true);
   }
 
-  // GTK propagates key events from parents to children.
-  // Make sure LockWindow will never handle key events.
-  virtual gboolean OnEventKey(GtkWidget* widget, GdkEventKey* event) OVERRIDE {
-    // Don't handle key event in the lock window.
-    return false;
-  }
-
   virtual gboolean OnButtonPress(GtkWidget* widget,
                                  GdkEventButton* event) OVERRIDE {
-    // Don't handle mouse event in the lock wnidow and
-    // nor propagate to child.
+    // Never propagate mouse events to parent.
     return true;
   }
 
@@ -72,6 +76,10 @@ class LockWindow : public views::NativeWidgetGtk {
     gtk_widget_grab_focus(toplevel_focus_widget_);
   }
 
+  virtual void HandleGtkGrabBroke() OVERRIDE {
+    webui_screen_locker_->HandleGtkGrabBroke();
+  }
+
   // Sets the widget to move the focus to when clearning the native
   // widget's focus.
   void set_toplevel_focus_widget(GtkWidget* widget) {
@@ -81,15 +89,35 @@ class LockWindow : public views::NativeWidgetGtk {
 
  private:
   // The widget we set focus to when clearning the focus on native
-  // widget.  In screen locker, gdk input is grabbed in GrabWidget,
-  // and resetting the focus by using gtk_window_set_focus seems to
-  // confuse gtk and doesn't let focus move to native widget under
-  // GrabWidget.
+  // widget.  Gdk input is grabbed in WebUIScreenLocker, and resetting the focus
+  // by using gtk_window_set_focus seems to confuse gtk and doesn't let focus
+  // move to native widget under this.
   GtkWidget* toplevel_focus_widget_;
 
+  // The WebUI screen locker.
+  chromeos::WebUIScreenLocker* webui_screen_locker_;
+
   DISALLOW_COPY_AND_ASSIGN(LockWindow);
 };
 
+// Define separate methods for each error code so that stack trace
+// will tell which error the grab failed with.
+void FailedWithGrabAlreadyGrabbed() {
+  LOG(FATAL) << "Grab already grabbed";
+}
+void FailedWithGrabInvalidTime() {
+  LOG(FATAL) << "Grab invalid time";
+}
+void FailedWithGrabNotViewable() {
+  LOG(FATAL) << "Grab not viewable";
+}
+void FailedWithGrabFrozen() {
+  LOG(FATAL) << "Grab frozen";
+}
+void FailedWithUnknownError() {
+  LOG(FATAL) << "Grab uknown";
+}
+
 }  // namespace
 
 namespace chromeos {
@@ -98,7 +126,13 @@ namespace chromeos {
 // WebUIScreenLocker implementation.
 
 WebUIScreenLocker::WebUIScreenLocker(ScreenLocker* screen_locker)
-    : ScreenLockerDelegate(screen_locker) {
+    : ScreenLockerDelegate(screen_locker),
+      drawn_(false),
+      input_grabbed_(false),
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
+      grab_failure_count_(0),
+      kbd_grab_status_(GDK_GRAB_INVALID_TIME),
+      mouse_grab_status_(GDK_GRAB_INVALID_TIME) {
 }
 
 void WebUIScreenLocker::LockScreen(bool unlock_on_input) {
@@ -106,7 +140,7 @@ void WebUIScreenLocker::LockScreen(bool unlock_on_input) {
 
   gfx::Rect bounds(gfx::Screen::GetMonitorAreaNearestWindow(NULL));
 
-  LockWindow* lock_window = new LockWindow();
+  LockWindow* lock_window = new LockWindow(this);
   lock_window_ = lock_window->GetWidget();
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
@@ -146,6 +180,12 @@ void WebUIScreenLocker::LockScreen(bool unlock_on_input) {
                  chrome::NOTIFICATION_LOGIN_USER_IMAGE_CHANGED,
                  content::NotificationService::AllSources());
 
+  ClearGtkGrab();
+
+  // Call this after lock_window_->Show(); otherwise the 1st invocation
+  // of gdk_xxx_grab() will always fail.
+  TryGrabAllInputs();
+
   // Add the window to its own group so that its grab won't be stolen if
   // gtk_grab_add() gets called on behalf on a non-screen-locker widget (e.g.
   // a modal dialog) -- see http://crosbug.com/8999.  We intentionally do this
@@ -159,11 +199,161 @@ void WebUIScreenLocker::LockScreen(bool unlock_on_input) {
   lock_window->set_toplevel_focus_widget(lock_window->window_contents());
 }
 
+void WebUIScreenLocker::OnGrabInputs() {
+  DVLOG(1) << "OnGrabInputs";
+  input_grabbed_ = true;
+  if (drawn_)
+    ScreenLockReady();
+}
+
+void WebUIScreenLocker::OnWindowManagerReady() {
+  DVLOG(1) << "OnClientEvent: drawn for lock";
+  drawn_ = true;
+  if (input_grabbed_)
+    ScreenLockReady();
+}
+
 void WebUIScreenLocker::ScreenLockReady() {
   ScreenLockerDelegate::ScreenLockReady();
   SetInputEnabled(true);
 }
 
+void WebUIScreenLocker::ClearGtkGrab() {
+  GtkWidget* current_grab_window;
+  // Grab gtk input first so that the menu holding gtk grab will
+  // close itself.
+  gtk_grab_add(webui_login_->native_view());
+
+  // Make sure there is no gtk grab widget so that gtk simply propagates
+  // an event.  GTK maintains grab widgets in a linked-list, so we need to
+  // remove until it's empty.
+  while ((current_grab_window = gtk_grab_get_current()) != NULL)
+    gtk_grab_remove(current_grab_window);
+}
+
+void WebUIScreenLocker::TryGrabAllInputs() {
+  // Grab on the RenderWidgetHostView hosting the WebUI login screen.
+  GdkWindow* grab_widget = webui_login_->dom_contents()->tab_contents()->
+      GetRenderWidgetHostView()->GetNativeView()->window;
+  // Grab x server so that we can atomically grab and take
+  // action when grab fails.
+  gdk_x11_grab_server();
+  gtk_grab_add(webui_login_->native_view());
+  if (kbd_grab_status_ != GDK_GRAB_SUCCESS)
+    kbd_grab_status_ = gdk_keyboard_grab(grab_widget, FALSE, GDK_CURRENT_TIME);
+  if (mouse_grab_status_ != GDK_GRAB_SUCCESS) {
+    mouse_grab_status_ =
+        gdk_pointer_grab(grab_widget,
+                         FALSE,
+                         static_cast<GdkEventMask>(
+                             GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
+                             GDK_POINTER_MOTION_MASK),
+                         NULL,
+                         NULL,
+                         GDK_CURRENT_TIME);
+  }
+  if ((kbd_grab_status_ != GDK_GRAB_SUCCESS ||
+       mouse_grab_status_ != GDK_GRAB_SUCCESS) &&
+      grab_failure_count_++ < kMaxGrabFailures) {
+    LOG(WARNING) << "Failed to grab inputs. Trying again in "
+                 << kRetryGrabIntervalMs << " ms: kbd="
+                 << kbd_grab_status_ << ", mouse=" << mouse_grab_status_;
+    TryUngrabOtherClients();
+    gdk_x11_ungrab_server();
+    MessageLoop::current()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&WebUIScreenLocker::TryGrabAllInputs,
+                   weak_factory_.GetWeakPtr()),
+        kRetryGrabIntervalMs);
+  } else {
+    gdk_x11_ungrab_server();
+    GdkGrabStatus status = kbd_grab_status_;
+    if (status == GDK_GRAB_SUCCESS) {
+      status = mouse_grab_status_;
+    }
+    switch (status) {
+      case GDK_GRAB_SUCCESS:
+        break;
+      case GDK_GRAB_ALREADY_GRABBED:
+        FailedWithGrabAlreadyGrabbed();
+        break;
+      case GDK_GRAB_INVALID_TIME:
+        FailedWithGrabInvalidTime();
+        break;
+      case GDK_GRAB_NOT_VIEWABLE:
+        FailedWithGrabNotViewable();
+        break;
+      case GDK_GRAB_FROZEN:
+        FailedWithGrabFrozen();
+        break;
+      default:
+        FailedWithUnknownError();
+        break;
+    }
+    DVLOG(1) << "Grab Success";
+    OnGrabInputs();
+  }
+}
+
+void WebUIScreenLocker::TryUngrabOtherClients() {
+#if !defined(NDEBUG)
+  {
+    int event_base, error_base;
+    int major, minor;
+    // Make sure we have XTest extension.
+    DCHECK(XTestQueryExtension(ui::GetXDisplay(),
+                               &event_base, &error_base,
+                               &major, &minor));
+  }
+#endif
+
+  // The following code is an attempt to grab inputs by closing
+  // supposedly opened menu. This happens when a plugin has a menu
+  // opened.
+  if (mouse_grab_status_ == GDK_GRAB_ALREADY_GRABBED ||
+      mouse_grab_status_ == GDK_GRAB_FROZEN) {
+    // Successfully grabbed the keyboard, but pointer is still
+    // grabbed by other client. Another attempt to close supposedly
+    // opened menu by emulating keypress at the left top corner.
+    Display* display = ui::GetXDisplay();
+    Window root, child;
+    int root_x, root_y, win_x, winy;
+    unsigned int mask;
+    XQueryPointer(display,
+                  ui::GetX11WindowFromGtkWidget(
+                      static_cast<LockWindow*>(lock_window_->native_widget())->
+                      window_contents()),
+                  &root, &child, &root_x, &root_y,
+                  &win_x, &winy, &mask);
+    XTestFakeMotionEvent(display, -1, -10000, -10000, CurrentTime);
+    XTestFakeButtonEvent(display, 1, True, CurrentTime);
+    XTestFakeButtonEvent(display, 1, False, CurrentTime);
+    // Move the pointer back.
+    XTestFakeMotionEvent(display, -1, root_x, root_y, CurrentTime);
+    XFlush(display);
+  } else if (kbd_grab_status_ == GDK_GRAB_ALREADY_GRABBED ||
+             kbd_grab_status_ == GDK_GRAB_FROZEN) {
+    // Successfully grabbed the pointer, but keyboard is still grabbed
+    // by other client. Another attempt to close supposedly opened
+    // menu by emulating escape key.  Such situation must be very
+    // rare, but handling this just in case
+    Display* display = ui::GetXDisplay();
+    KeyCode escape = XKeysymToKeycode(display, XK_Escape);
+    XTestFakeKeyEvent(display, escape, True, CurrentTime);
+    XTestFakeKeyEvent(display, escape, False, CurrentTime);
+    XFlush(display);
+  }
+}
+
+void WebUIScreenLocker::HandleGtkGrabBroke() {
+  // Input should never be stolen from ScreenLocker once it's
+  // grabbed.  If this happens, it's a bug and has to be fixed. We
+  // let chrome crash to get a crash report and dump, and
+  // SessionManager will terminate the session to logout.
+  CHECK_NE(GDK_GRAB_SUCCESS, kbd_grab_status_);
+  CHECK_NE(GDK_GRAB_SUCCESS, mouse_grab_status_);
+}
+
 void WebUIScreenLocker::OnAuthenticate() {
 }
 
@@ -210,7 +400,7 @@ void WebUIScreenLocker::OnClientEvent(GtkWidget* widge, GdkEventClient* event) {
   WmIpc::Message msg;
   WmIpc::instance()->DecodeMessage(*event, &msg);
   if (msg.type() == WM_IPC_MESSAGE_CHROME_NOTIFY_SCREEN_REDRAWN_FOR_LOCK)
-    ScreenLockReady();
+    OnWindowManagerReady();
 }
 
 ////////////////////////////////////////////////////////////////////////////////