Generalize and refactor DeviceSensorEvent* architecture to support multi-event type targets.

Source/core/frame/DeviceEventControllerBase.cpp

Index: Source/core/frame/DeviceEventControllerBase.cpp
diff --git a/Source/core/frame/DeviceEventControllerBase.cpp b/Source/core/frame/DeviceEventControllerBase.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5df24451c7f92368da36ca91d5d721ebe6bded29
--- /dev/null
+++ b/Source/core/frame/DeviceEventControllerBase.cpp
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2014 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "core/frame/DeviceEventControllerBase.h"
+
+#include "core/page/Page.h"
+
+namespace WebCore {
+
+DeviceEventControllerBase::DeviceEventControllerBase(Page* page)
+    : PageLifecycleObserver(page)
+    , m_hasEventListener(false)
+    , m_isActive(false)
+    , m_timer(this, &DeviceEventControllerBase::oneShotCallback)
+{
+}
+
+DeviceEventControllerBase::~DeviceEventControllerBase()
+{
+}
+
+void DeviceEventControllerBase::oneShotCallback(Timer<DeviceEventControllerBase>* timer)
+{
+    ASSERT_UNUSED(timer, timer == &m_timer);
+    ASSERT(isInvokeInitialUpdate());
+
+    m_timer.stop();

[Inactive, 2014/06/03 13:49:33]

Why do we need to stop the timer? It is one-shot.

[timvolodine, 2014/06/03 18:45:54]

yeah right it's one shot. added an "non-active" assert. Done.

+    didUpdateData();
+}
+
+void DeviceEventControllerBase::startUpdating()
+{
+    if (m_isActive)
+        return;
+
+    if (isInvokeInitialUpdate() && !m_timer.isActive()) {
+        // Make sure to fire the data as soon as possible.
+        m_timer.startOneShot(0, FROM_HERE);
+    }
+
+    registerWithDispatcher();
+    m_isActive = true;
+}
+
+void DeviceEventControllerBase::stopUpdating()
+{
+    if (!m_isActive)
+        return;
+
+    if (m_timer.isActive())
+        m_timer.stop();
+
+    unregisterWithDispatcher();
+    m_isActive = false;
+}
+
+void DeviceEventControllerBase::pageVisibilityChanged()
+{
+    if (!m_hasEventListener)
+        return;
+
+    if (page()->visibilityState() == PageVisibilityStateVisible)
+        startUpdating();
+    else
+        stopUpdating();
+}
+
+} // namespace WebCore