Fix regression: empty tooltip appears in Linux and Chrome OS

ui/views/corewm/tooltip_controller_unittest.cc

 // Copyright (c) 2013 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 "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "ui/aura/client/cursor_client.h"
@@ skipping 188 matching lines @@
 
   EXPECT_TRUE(helper_->IsTooltipVisible());
   generator_->MoveMouseBy(1, 0);
 
   EXPECT_TRUE(helper_->IsTooltipVisible());
   EXPECT_EQ(expected_tooltip, aura::client::GetTooltipText(GetWindow()));
   EXPECT_EQ(expected_tooltip, helper_->GetTooltipText());
   EXPECT_EQ(GetWindow(), helper_->GetTooltipWindow());
 }
 
+TEST_F(TooltipControllerTest, HideEmptyTooltip) {
+  // TODO: these tests use GetContext(). That should go away for aura-mus
+  // client. http://crbug.com/663781.
+  if (IsMus())
+    return;
+
+  view_->set_tooltip_text(ASCIIToUTF16("Tooltip Text"));
+  EXPECT_EQ(base::string16(), helper_->GetTooltipText());
+  EXPECT_EQ(NULL, helper_->GetTooltipWindow());
+
+  generator_->MoveMouseToCenterOf(GetWindow());
+  generator_->MoveMouseBy(1, 0);
+  EXPECT_TRUE(helper_->IsTooltipVisible());
+
+  view_->set_tooltip_text(ASCIIToUTF16("    "));
+  generator_->MoveMouseBy(1, 0);
+  EXPECT_FALSE(helper_->IsTooltipVisible());
+}
+
 #if defined(OS_CHROMEOS)
 // crbug.com/664370.
 TEST_F(TooltipControllerTest, MaxWidth) {
   // TODO: these tests use GetContext(). That should go away for mus client.
   // http://crbug.com/663781.
   if (IsMus())
     return;
 
   base::string16 text = base::ASCIIToUTF16(
       "Really really realy long long long long  long tooltips that exceeds max "
@@ skipping 646 matching lines @@
   generator_->MoveMouseRelativeTo(GetWindow(), center);
   tooltip_bounds1 = test_tooltip_->location();
 
   EXPECT_NE(tooltip_bounds1_1, tooltip_bounds1);
   EXPECT_EQ(reference_string, helper_->GetTooltipText());
 }
 
 }  // namespace test
 }  // namespace corewm
 }  // namespace views