Fix MouseMove event handling when opening a new tab with middle click.

When opening a new tab by middle clicking on a link in a web page, two
MouseMove events are sent to Chromium consecutively, without getting
proper acknowledgment events, which causes further move events not
to be handled properly.
Fix consists in preventing the second move event from being sent.

Change-Id: Ia0a64698476226e472faa53f75b51dfb6ed477c9
Task-number: QTBUG-50031
Reviewed-by: Joerg Bornemann <[email protected]>

Author: alcroito

src/core/render_widget_host_view_qt.cpp

@@ -747,6 +747,10 @@ bool RenderWidgetHostViewQt::forwardEvent(QEvent *event)
         Focus(); // Fall through.
     case QEvent::MouseButtonRelease:
     case QEvent::MouseMove:
+        // Skip second MouseMove event when a window is being adopted, so that Chromium
+        // can properly handle further move events.
+        if (m_adapterClient->isBeingAdopted())
+            return false;
         handleMouseEvent(static_cast<QMouseEvent*>(event));
         break;
     case QEvent::KeyPress:

src/core/web_contents_adapter_client.h

@@ -159,6 +159,7 @@ class QWEBENGINE_EXPORT WebContentsAdapterClient {
     virtual void focusContainer() = 0;
     virtual void unhandledKeyEvent(QKeyEvent *event) = 0;
     virtual void adoptNewWindow(WebContentsAdapter *newWebContents, WindowOpenDisposition disposition, bool userGesture, const QRect & initialGeometry) = 0;
+    virtual bool isBeingAdopted() = 0;
     virtual void close() = 0;
     virtual bool contextMenuRequested(const WebEngineContextMenuData&) = 0;
     virtual void navigationRequested(int navigationType, const QUrl &url, int &navigationRequestAction, bool isMainFrame) = 0;

src/webengine/api/qquickwebengineview.cpp

@@ -421,6 +421,11 @@ void QQuickWebEngineViewPrivate::adoptNewWindow(WebContentsAdapter *newWebConten
     Q_EMIT q->newViewRequested(&request);
 }
 
+bool QQuickWebEngineViewPrivate::isBeingAdopted()
+{
+    return false;
+}
+
 void QQuickWebEngineViewPrivate::close()
 {
     // Not implemented yet.

src/webengine/api/qquickwebengineview_p_p.h

@@ -141,6 +141,7 @@ class Q_WEBENGINE_PRIVATE_EXPORT QQuickWebEngineViewPrivate : public QtWebEngine
     virtual void focusContainer() Q_DECL_OVERRIDE;
     virtual void unhandledKeyEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
     virtual void adoptNewWindow(QtWebEngineCore::WebContentsAdapter *newWebContents, WindowOpenDisposition disposition, bool userGesture, const QRect &) Q_DECL_OVERRIDE;
+    virtual bool isBeingAdopted() Q_DECL_OVERRIDE;
     virtual void close() Q_DECL_OVERRIDE;
     virtual void requestFullScreen(bool) Q_DECL_OVERRIDE;
     virtual bool isFullScreen() const Q_DECL_OVERRIDE;

src/webenginewidgets/api/qwebenginepage.cpp

@@ -185,6 +185,7 @@ QWebEnginePagePrivate::QWebEnginePagePrivate(QWebEngineProfile *_profile)
     , view(0)
     , isLoading(false)
     , scriptCollection(new QWebEngineScriptCollectionPrivate(browserContextAdapter()->userScriptController(), adapter.data()))
+    , m_isBeingAdopted(false)
 {
     memset(actions, 0, sizeof(actions));
 }
@@ -298,14 +299,35 @@ void QWebEnginePagePrivate::adoptNewWindow(WebContentsAdapter *newWebContents, W
 {
     Q_Q(QWebEnginePage);
     Q_UNUSED(userGesture);
+
     QWebEnginePage *newPage = q->createWindow(toWindowType(disposition));
+
+    // Mark the new page as being in the process of being adopted, so that a second mouse move event
+    // sent by newWebContents->initialize() gets filtered in RenderWidgetHostViewQt::forwardEvent.
+    // The first mouse move event is being sent by q->createWindow(). This is necessary because
+    // Chromium does not get a mouse move acknowledgment message between the two events, and
+    // InputRouterImpl::ProcessMouseAck is not executed, thus all subsequent mouse move events
+    // get coalesced together, and don't get processed at all.
+    // The mouse move events are actually sent as a result of show() being called on
+    // RenderWidgetHostViewQtDelegateWidget, both when creating the window and when initialize is
+    // called.
+    newPage->d_func()->m_isBeingAdopted = true;
+
     // Overwrite the new page's WebContents with ours.
     if (newPage && newPage->d_func() != this) {
         newPage->d_func()->adapter = newWebContents;
         newWebContents->initialize(newPage->d_func());
         if (!initialGeometry.isEmpty())
             emit newPage->geometryChangeRequested(initialGeometry);
     }
+
+    // Page has finished the adoption process.
+    newPage->d_func()->m_isBeingAdopted = false;
+}
+
+bool QWebEnginePagePrivate::isBeingAdopted()
+{
+    return m_isBeingAdopted;
 }
 
 void QWebEnginePagePrivate::close()

src/webenginewidgets/api/qwebenginepage_p.h

@@ -136,6 +136,7 @@ class QWebEnginePagePrivate : public QtWebEngineCore::WebContentsAdapterClient
     virtual void focusContainer() Q_DECL_OVERRIDE;
     virtual void unhandledKeyEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
     virtual void adoptNewWindow(QtWebEngineCore::WebContentsAdapter *newWebContents, WindowOpenDisposition disposition, bool userGesture, const QRect &initialGeometry) Q_DECL_OVERRIDE;
+    virtual bool isBeingAdopted() Q_DECL_OVERRIDE;
     virtual void close() Q_DECL_OVERRIDE;
     virtual bool contextMenuRequested(const QtWebEngineCore::WebEngineContextMenuData &data) Q_DECL_OVERRIDE;
     virtual void navigationRequested(int navigationType, const QUrl &url, int &navigationRequestAction, bool isMainFrame) Q_DECL_OVERRIDE;
@@ -181,6 +182,7 @@ class QWebEnginePagePrivate : public QtWebEngineCore::WebContentsAdapterClient
     QtWebEngineCore::WebEngineContextMenuData m_menuData;
     bool isLoading;
     QWebEngineScriptCollection scriptCollection;
+    bool m_isBeingAdopted;
 
     mutable CallbackDirectory m_callbacks;
     mutable QAction *actions[QWebEnginePage::WebActionCount];