Do not show a tooltip same as the previous one.

If a tooltip is closed by a keyboard event and the mouse cursor was
not moved, the same tooltip was shown again after some delay only on
Windows.  Blink receives native mousemove events repeatedly on Windows
even if the mouse cursor is not moved.

ChromeClient saves the last tooltip string and the last mouse position, and
do not call virtual setToolTip() if they are not changed. This CL not only
fixes the bug, but also reduces unnecessary IPC messages for tooltip.

BUG=557660
TEST=automated

Review URL: https://codereview.chromium.org/1500813004

Cr-Commit-Position: refs/heads/master@{#363174}
(cherry picked from commit 91db68e)

Review URL: https://codereview.chromium.org/1504743002 .

Cr-Commit-Position: refs/branch-heads/2564@{#248}
Cr-Branched-From: 1283eca-refs/heads/master@{#359700}

third_party/WebKit/Source/core/core.gypi

@@ -3896,6 +3896,7 @@
             'loader/LinkHeaderTest.cpp',
             'loader/LinkLoaderTest.cpp',
             'loader/MixedContentCheckerTest.cpp',
+            'page/ChromeClientTest.cpp',
             'page/ContextMenuControllerTest.cpp',
             'page/NetworkStateNotifierTest.cpp',
             'page/PagePopupClientTest.cpp',

third_party/WebKit/Source/core/input/EventHandler.cpp

@@ -3151,7 +3151,7 @@ bool EventHandler::handleAccessKey(const PlatformKeyboardEvent& evt)
 bool EventHandler::keyEvent(const PlatformKeyboardEvent& initialKeyEvent)
 {
     RefPtrWillBeRawPtr<FrameView> protector(m_frame->view());
-    m_frame->chromeClient().setToolTip(String(), LTR);
+    m_frame->chromeClient().clearToolTip();
 
     if (initialKeyEvent.windowsVirtualKeyCode() == VK_CAPITAL)
         capsLockStateMayHaveChanged();

third_party/WebKit/Source/core/page/ChromeClient.cpp

@@ -167,9 +167,20 @@ void ChromeClient::setToolTip(const HitTestResult& result)
         }
     }
 
+    if (m_lastToolTipPoint == result.hitTestLocation().point() && m_lastToolTipText == toolTip)
+        return;
+    m_lastToolTipPoint = result.hitTestLocation().point();
+    m_lastToolTipText = toolTip;
     setToolTip(toolTip, toolTipDirection);
 }
 
+void ChromeClient::clearToolTip()
+{
+    // Do not check m_lastToolTip* and do not update them intentionally.
+    // We don't want to show tooltips with same content after clearToolTip().
+    setToolTip(String(), LTR);
+}
+
 void ChromeClient::print(LocalFrame* frame)
 {
     // Defer loads in case the client method runs a new event loop that would

third_party/WebKit/Source/core/page/ChromeClient.h

@@ -22,6 +22,7 @@
 #ifndef ChromeClient_h
 #define ChromeClient_h
 
+#include "base/gtest_prod_util.h"
 #include "core/CoreExport.h"
 #include "core/dom/AXObjectCache.h"
 #include "core/frame/ConsoleTypes.h"
@@ -155,6 +156,7 @@ class CORE_EXPORT ChromeClient : public HostWindow {
 
     void mouseDidMoveOverElement(const HitTestResult&);
     virtual void setToolTip(const String&, TextDirection) = 0;
+    void clearToolTip();
 
     void print(LocalFrame*);
 
@@ -270,6 +272,11 @@ class CORE_EXPORT ChromeClient : public HostWindow {
 private:
     bool canOpenModalIfDuringPageDismissal(Frame* mainFrame, DialogType, const String& message);
     void setToolTip(const HitTestResult&);
+
+    LayoutPoint m_lastToolTipPoint;
+    String m_lastToolTipText;
+
+    FRIEND_TEST_ALL_PREFIXES(ChromeClientTest, SetToolTipFlood);
 };
 
 } // namespace blink

third_party/WebKit/Source/core/page/ChromeClientTest.cpp

@@ -0,0 +1,70 @@
+// Copyright 2015 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 "config.h"
+#include "core/page/ChromeClient.h"
+
+#include "core/dom/Document.h"
+#include "core/layout/HitTestResult.h"
+#include "core/loader/EmptyClients.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+namespace {
+
+class ChromeClientToolTipLogger : public EmptyChromeClient {
+public:
+    void setToolTip(const String& text, TextDirection) override
+    {
+        m_toolTipForLastSetToolTip = text;
+    }
+
+    String toolTipForLastSetToolTip() const { return m_toolTipForLastSetToolTip; }
+    void clearToolTipForLastSetToolTip() { m_toolTipForLastSetToolTip = String(); }
+
+private:
+    String m_toolTipForLastSetToolTip;
+};
+
+} // anonymous namespace
+
+class ChromeClientTest : public testing::Test {
+};
+
+TEST_F(ChromeClientTest, SetToolTipFlood)
+{
+    ChromeClientToolTipLogger logger;
+    ChromeClient* client = &logger;
+    HitTestResult result(HitTestRequest(HitTestRequest::Move), LayoutPoint(10, 20));
+    RefPtrWillBeRawPtr<Document> doc = Document::create();
+    RefPtrWillBeRawPtr<Element> element = HTMLElement::create(HTMLNames::divTag, *doc);
+    element->setAttribute(HTMLNames::titleAttr, "tooltip");
+    result.setInnerNode(element.get());
+
+    client->setToolTip(result);
+    EXPECT_EQ("tooltip", logger.toolTipForLastSetToolTip());
+
+    // seToolTip(HitTestResult) again in the same condition.
+    logger.clearToolTipForLastSetToolTip();
+    client->setToolTip(result);
+    // setToolTip(String,TextDirection) should not be called.
+    EXPECT_EQ(String(), logger.toolTipForLastSetToolTip());
+
+    // Cancel the tooltip, and setToolTip(HitTestResult) again.
+    client->clearToolTip();
+    logger.clearToolTipForLastSetToolTip();
+    client->setToolTip(result);
+    // setToolTip(String,TextDirection) should not be called.
+    EXPECT_EQ(String(), logger.toolTipForLastSetToolTip());
+
+    logger.clearToolTipForLastSetToolTip();
+    element->setAttribute(HTMLNames::titleAttr, "updated");
+    client->setToolTip(result);
+    // setToolTip(String,TextDirection) should be called because tooltip string
+    // is different from the last one.
+    EXPECT_EQ("updated", logger.toolTipForLastSetToolTip());
+}
+
+} // namespace blink