[sailfish-browser] Virtualize background tabs when another applicatio…

…n is opened

Current implementation virtualizes backgrounded tabs when low memory
notification (warning / critical) is received even if the browser is
at foreground. Virtualizing backgrounded tabs when another application
is brought foreground guarantees that there are no background tabs
when another application is running regardless of low memory
notification.

src/webpages.cpp

@@ -35,6 +35,9 @@ static const qint64 gMemoryPressureTimeout = 600 * 1000; // 600 sec
 // In normal cases gLowMemoryEnabled is true. Can be disabled e.g. for test runs.
 static const bool gLowMemoryEnabled = qgetenv("LOW_MEMORY_DISABLED").isEmpty();
 
+static const QLatin1String gLowMemoryWarning("warning");
+static const QLatin1String gLowMemoryCritical("critical");
+
 WebPages::WebPages(QObject *parent)
     : QObject(parent)
     , m_backgroundTimestamp(0)
@@ -58,15 +61,31 @@ void WebPages::initialize(DeclarativeWebContainer *webContainer, QQmlComponent *
     }
 
     connect(webContainer, SIGNAL(foregroundChanged()), this, SLOT(updateBackgroundTimestamp()));
+    connect(webContainer, SIGNAL(backgroundChanged()), this, SLOT(virtualizeInactive()));
 }
 
 void WebPages::updateBackgroundTimestamp()
 {
+    // In Switcher.
     if (!m_webContainer->foreground()) {
         m_backgroundTimestamp = QDateTime::currentMSecsSinceEpoch();
     }
 }
 
+/*!
+ * Virtualize pages that are inactive (all but the first).
+ * This also takes a time stamp that is later used to
+ * trigger gc and heap minimizing when low memory notifacations
+ * is recieved after some time.
+ */
+void WebPages::virtualizeInactive()
+{
+    // Another application got opened.
+    if (m_webContainer->background()) {
+        handleMemNotify(gLowMemoryWarning);
+    }
+}
+
 bool WebPages::initialized() const
 {
     return m_webContainer && m_webPageComponent;
@@ -188,7 +207,7 @@ void WebPages::dumpPages() const
 
 void WebPages::handleMemNotify(const QString &memoryLevel)
 {
-    if (memoryLevel == QString("warning") || memoryLevel == QString("critical")) {
+    if (memoryLevel == gLowMemoryWarning || memoryLevel == gLowMemoryCritical) {
         m_activePages.virtualizeInactive();
 
         if (!m_webContainer->foreground() &&

src/webpages.h

@@ -55,6 +55,7 @@ class WebPages : public QObject
 private slots:
     void handleMemNotify(const QString &memoryLevel);
     void updateBackgroundTimestamp();
+    void virtualizeInactive();
 
 private:
     void updateStates(DeclarativeWebPage *oldActivePage, DeclarativeWebPage *newActivePage);