Bug 1487082 - Resolve potential for build bustage regarding bad implicit conversion constructors

* Part 1: make conversion CTORs explicit.
  Minor tweaks to conform with new(ish) static analysis rule which flags up implicit single-argument conversion constructors.
* Part 2: fix a couple of double-mRefCnt declaration errors.
* Part 3: Fix unsafe use of NS_ConvertASCIItoUTF16().

Tag #1273

mailnews/imap/src/nsAutoSyncState.h

@@ -56,7 +56,7 @@ public:
   NS_DECL_NSIAUTOSYNCSTATE
   NS_DECL_NSIURLLISTENER
 
-  nsAutoSyncState(nsImapMailFolder *aOwnerFolder, PRTime aLastSyncTime = 0UL);
+  explicit nsAutoSyncState(nsImapMailFolder *aOwnerFolder, PRTime aLastSyncTime = 0UL);
 
   /// Called by owner folder when new headers are fetched from the server
   void OnNewHeaderFetchCompleted(const nsTArray<nsMsgKey> &aMsgKeyList);

mailnews/imap/src/nsImapFlagAndUidState.h

@@ -20,7 +20,7 @@ class nsImapFlagAndUidState : public nsIImapFlagAndUidState
 {
 public:
     NS_DECL_THREADSAFE_ISUPPORTS
-    nsImapFlagAndUidState(int numberOfMessages);
+    explicit nsImapFlagAndUidState(int numberOfMessages);
 
     NS_DECL_NSIIMAPFLAGANDUIDSTATE
 

mailnews/imap/src/nsImapMailFolder.cpp

@@ -6363,7 +6363,7 @@ NS_IMETHODIMP nsImapMailFolder::GetOtherUsersWithAccess(
 class AdoptUTF8StringEnumerator final : public nsIUTF8StringEnumerator
 {
 public:
-  AdoptUTF8StringEnumerator(nsTArray<nsCString>* array) :
+  explicit AdoptUTF8StringEnumerator(nsTArray<nsCString>* array) :
     mStrings(array), mIndex(0)
   {}
 

mailnews/imap/src/nsImapMailFolder.h

@@ -115,7 +115,7 @@ class nsImapMailFolder;
 class nsMsgIMAPFolderACL
 {
 public:
-  nsMsgIMAPFolderACL(nsImapMailFolder *folder);
+  explicit nsMsgIMAPFolderACL(nsImapMailFolder *folder);
   ~nsMsgIMAPFolderACL();
 
   bool SetFolderRightsForUser(const nsACString& userName, const nsACString& rights);

mailnews/imap/src/nsImapProtocol.cpp

@@ -1057,7 +1057,7 @@ void nsImapProtocol::ReleaseUrlState(bool rerunning)
 
 class nsImapThreadShutdownEvent : public mozilla::Runnable {
 public:
-  nsImapThreadShutdownEvent(nsIThread *thread) : mThread(thread) {
+  explicit nsImapThreadShutdownEvent(nsIThread *thread) : mThread(thread) {
   }
   NS_IMETHOD Run() {
     mThread->Shutdown();
@@ -9580,7 +9580,7 @@ nsresult nsImapMockChannel::ReadFromMemCache(nsICacheEntry *entry)
 class nsReadFromImapConnectionFailure : public mozilla::Runnable
 {
 public:
-  nsReadFromImapConnectionFailure(nsImapMockChannel *aChannel)
+  explicit nsReadFromImapConnectionFailure(nsImapMockChannel *aChannel)
     : mImapMockChannel(aChannel)
   {}
 

mailnews/imap/src/nsImapSearchResults.h

@@ -25,7 +25,7 @@ private:
 
 class nsImapSearchResultIterator {
 public:
-    nsImapSearchResultIterator(nsImapSearchResultSequence &sequence);
+    explicit nsImapSearchResultIterator(nsImapSearchResultSequence &sequence);
     virtual ~nsImapSearchResultIterator();
     
     void  ResetIterator();

mailnews/imap/src/nsImapServerResponseParser.h

@@ -28,7 +28,7 @@ class nsCString;
 class nsImapServerResponseParser : public nsIMAPGenericParser
 {
 public:
-  nsImapServerResponseParser(nsImapProtocol &imapConnection);
+  explicit nsImapServerResponseParser(nsImapProtocol &imapConnection);
   virtual ~nsImapServerResponseParser();
 
   // Overridden from the base parser class

mailnews/imap/src/nsSyncRunnableHelpers.h

@@ -27,7 +27,7 @@
 class StreamListenerProxy final : public nsIStreamListener
 {
 public:
-  StreamListenerProxy(nsIStreamListener* receiver)
+  explicit StreamListenerProxy(nsIStreamListener* receiver)
     : mReceiver(receiver)
   { }
 
@@ -45,7 +45,7 @@ private:
 class ImapMailFolderSinkProxy final : public nsIImapMailFolderSink
 {
 public:
-  ImapMailFolderSinkProxy(nsIImapMailFolderSink* receiver)
+  explicit ImapMailFolderSinkProxy(nsIImapMailFolderSink* receiver)
     : mReceiver(receiver)
   {
     NS_ASSERTION(receiver, "Don't allow receiver is nullptr");
@@ -64,7 +64,7 @@ private:
 class ImapServerSinkProxy final : public nsIImapServerSink
 {
 public:
-  ImapServerSinkProxy(nsIImapServerSink* receiver)
+  explicit ImapServerSinkProxy(nsIImapServerSink* receiver)
     : mReceiver(receiver)
   { }
 
@@ -82,7 +82,7 @@ private:
 class ImapMessageSinkProxy final : public nsIImapMessageSink
 {
 public:
-  ImapMessageSinkProxy(nsIImapMessageSink* receiver)
+  explicit ImapMessageSinkProxy(nsIImapMessageSink* receiver)
     : mReceiver(receiver)
   { }
 
@@ -99,7 +99,7 @@ private:
 class ImapProtocolSinkProxy final : public nsIImapProtocolSink
 {
 public:
-  ImapProtocolSinkProxy(nsIImapProtocolSink* receiver)
+  explicit ImapProtocolSinkProxy(nsIImapProtocolSink* receiver)
     : mReceiver(receiver)
   { }