Try to fix the possible bug in base::Time:Now() that can cause the crashing later in icu code calle…

ash/system/date/date_view.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/date/date_view.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
 #include "base/i18n/time_formatting.h"
@@ skipping 163 matching lines @@
 
 TimeView::~TimeView() {
 }
 
 void TimeView::UpdateTimeFormat() {
   hour_type_ = ash::Shell::GetInstance()->tray_delegate()->GetHourClockType();
   UpdateText();
 }
 
 void TimeView::UpdateTextInternal(const base::Time& now) {
+  // Just in case |now| is null, do NOT update time; otherwise, it will
+  // crash icu code by calling into base::TimeFormatTimeOfDayWithHourClockType,
+  // see details in crbug.com/147570.
+  if (now.is_null()) {
+    LOG(ERROR) << "Received null value from base::Time |now| in argument";
+    return;
+  }
+
   string16 current_time = base::TimeFormatTimeOfDayWithHourClockType(
       now, hour_type_, base::kDropAmPm);
   label_->SetText(current_time);
   label_->SetTooltipText(base::TimeFormatFriendlyDate(now));
 
   // Calculate vertical clock layout labels.
   size_t colon_pos = current_time.find(ASCIIToUTF16(":"));
   string16 hour = current_time.substr(0, colon_pos);
   string16 minute = current_time.substr(colon_pos + 1);
   label_hour_left_->SetText(hour.substr(0, 1));
@@ skipping 73 matching lines @@
 void TimeView::SetupLabel(views::Label* label) {
   label->set_owned_by_client();
   SetupLabelForTray(label);
   gfx::Font font = label->font();
   label->SetFont(font.DeriveFont(0, font.GetStyle() & ~gfx::Font::BOLD));
 }
 
 }  // namespace tray
 }  // namespace internal
 }  // namespace ash