Make FrameDestructionObserver::m_frame a private.

Source/core/plugins/DOMPluginArray.cpp

Index: Source/core/plugins/DOMPluginArray.cpp
diff --git a/Source/core/plugins/DOMPluginArray.cpp b/Source/core/plugins/DOMPluginArray.cpp
index 4c711e9c6b0d3b3f024013f0ea4171d59a21005a..956898963c257cdaef85892111c8aa806d4e8f6a 100644
--- a/Source/core/plugins/DOMPluginArray.cpp
+++ b/Source/core/plugins/DOMPluginArray.cpp
@@ -54,14 +54,14 @@ PassRefPtrWillBeRawPtr<DOMPlugin> DOMPluginArray::item(unsigned index)
     const Vector<PluginInfo>& plugins = data->plugins();
     if (index >= plugins.size())
         return nullptr;
-    return DOMPlugin::create(data, m_frame, index).get();
+    return DOMPlugin::create(data, m_frame, index);
 }
 
 bool DOMPluginArray::canGetItemsForName(const AtomicString& propertyName)
 {
     PluginData* data = pluginData();
     if (!data)
-        return 0;
+        return false;
     const Vector<PluginInfo>& plugins = data->plugins();
     for (unsigned i = 0; i < plugins.size(); ++i) {
         if (plugins[i].name == propertyName)
@@ -78,7 +78,7 @@ PassRefPtrWillBeRawPtr<DOMPlugin> DOMPluginArray::namedItem(const AtomicString&
     const Vector<PluginInfo>& plugins = data->plugins();
     for (unsigned i = 0; i < plugins.size(); ++i) {
         if (plugins[i].name == propertyName)
-            return DOMPlugin::create(data, m_frame, i).get();
+            return DOMPlugin::create(data, m_frame, i);
     }
     return nullptr;
 }
@@ -95,10 +95,10 @@ void DOMPluginArray::refresh(bool reload)
 PluginData* DOMPluginArray::pluginData() const
 {
     if (!m_frame)
-        return 0;
+        return nullptr;
     Page* page = m_frame->page();
     if (!page)
-        return 0;
+        return nullptr;
     return page->pluginData();
 }