Fix regression: empty tooltip appears in Linux and Chrome OS

ui/views/corewm/tooltip_controller.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 "ui/views/corewm/tooltip_controller.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 290 matching lines @@
     tooltip_shown_timer_.Stop();
     tooltip_text_ = tooltip_text;
     base::string16 trimmed_text =
         gfx::TruncateString(tooltip_text_, kMaxTooltipLength, gfx::WORD_BREAK);
     // If the string consists entirely of whitespace, then don't both showing it
     // (an empty tooltip is useless).
     base::TrimWhitespace(trimmed_text, base::TRIM_ALL,
                          &tooltip_text_whitespace_trimmed_);
     if (tooltip_text_whitespace_trimmed_.empty()) {
       tooltip_->Hide();
+      if (tooltip_defer_timer_.IsRunning()) {

[sky, 2017/01/26 18:25:37]

no {}

[chengx, 2017/01/26 21:04:03]

Done.

+        tooltip_defer_timer_.Reset();
+      }
     } else if (tooltip_show_delayed_) {
       // Initialize the one-shot timer to show the tooltip in a while.
       // If there is already a request queued then cancel it and post the new
       // request. This ensures that tooltip won't show up too early.
       // The delayed appearance of a tooltip is by default.
       if (tooltip_defer_timer_.IsRunning()) {
         tooltip_defer_timer_.Reset();
       } else {
         tooltip_defer_timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(
                                                   kDelayForTooltipUpdateInMs),
                                    this, &TooltipController::ShowTooltip);
       }
     } else {
       ShowTooltip();  // Allow tooltip to show up without delay for unit tests.
     }
   }
 }
 
 void TooltipController::ShowTooltip() {
-  if (!tooltip_window_)
+  if (!tooltip_window_ || tooltip_text_whitespace_trimmed_.empty())
     return;
   gfx::Point widget_loc =
       curr_mouse_loc_ + tooltip_window_->GetBoundsInScreen().OffsetFromOrigin();
   tooltip_->SetText(tooltip_window_, tooltip_text_whitespace_trimmed_,
                     widget_loc);
   tooltip_->Show();
   int timeout = GetTooltipShownTimeout();
   if (timeout > 0) {
     tooltip_shown_timer_.Start(FROM_HERE,
                                base::TimeDelta::FromMilliseconds(timeout), this,
@@ skipping 38 matching lines @@
     return;
   if (tooltip_window_)
     tooltip_window_->RemoveObserver(this);
   tooltip_window_ = target;
   if (tooltip_window_)
     tooltip_window_->AddObserver(this);
 }
 
 }  // namespace corewm
 }  // namespace views