Make FrameDestructionObserver::m_frame a private.

Source/core/plugins/DOMPlugin.cpp

Index: Source/core/plugins/DOMPlugin.cpp
diff --git a/Source/core/plugins/DOMPlugin.cpp b/Source/core/plugins/DOMPlugin.cpp
index ebaff997579d9e75c6e61779e33c61126ccc059a..69f998f4d9bbb25ecd7925b5a6e773d1c932e2f4 100644
--- a/Source/core/plugins/DOMPlugin.cpp
+++ b/Source/core/plugins/DOMPlugin.cpp
@@ -70,7 +70,7 @@ PassRefPtrWillBeRawPtr<DOMMimeType> DOMPlugin::item(unsigned index)
     const Vector<MimeClassInfo>& mimes = m_pluginData->mimes();
     for (unsigned i = 0; i < mimes.size(); ++i) {
         if (mimes[i] == mime && m_pluginData->mimePluginIndices()[i] == m_index)
-            return DOMMimeType::create(m_pluginData.get(), m_frame, i).get();
+            return DOMMimeType::create(m_pluginData.get(), frame(), i);
     }
     return nullptr;
 }
@@ -87,9 +87,10 @@ bool DOMPlugin::canGetItemsForName(const AtomicString& propertyName)
 PassRefPtrWillBeRawPtr<DOMMimeType> DOMPlugin::namedItem(const AtomicString& propertyName)
 {
     const Vector<MimeClassInfo>& mimes = m_pluginData->mimes();
-    for (unsigned i = 0; i < mimes.size(); ++i)
+    for (unsigned i = 0; i < mimes.size(); ++i) {
         if (mimes[i].type == propertyName)
-            return DOMMimeType::create(m_pluginData.get(), m_frame, i).get();
+            return DOMMimeType::create(m_pluginData.get(), frame(), i);
+    }
     return nullptr;
 }