Remove the individual global search provider boolean flags and replace them with with a Q_FLAGS enum. Also add a flag for "probably has remote album art"

src/globalsearch/digitallyimportedsearchprovider.cpp

@@ -24,7 +24,7 @@ DigitallyImportedSearchProvider::DigitallyImportedSearchProvider(
     : SimpleSearchProvider(parent),
       service_(service)
 {
-  Init(service_->name(), service->url_scheme(), service_->icon(), false, false);
+  Init(service_->name(), service->url_scheme(), service_->icon());
   icon_ = ScaleAndPad(QImage(service_->icon_path()));
 
   set_safe_words(QStringList() << "sky.fm" << "skyfm" << "di.fm" << "difm"

src/globalsearch/groovesharksearchprovider.cpp

@@ -31,7 +31,9 @@ GroovesharkSearchProvider::GroovesharkSearchProvider(QObject* parent)
 void GroovesharkSearchProvider::Init(GroovesharkService* service) {
   service_ = service;
   SearchProvider::Init("Grooveshark", "grooveshark",
-                       QIcon(":providers/grooveshark.png"), true, false);
+                       QIcon(":providers/grooveshark.png"),
+                       WantsDelayedQueries | ArtIsProbablyRemote);
+
   connect(service_, SIGNAL(SimpleSearchResults(int, SongList)),
           SLOT(SearchDone(int, SongList)));
   connect(service_, SIGNAL(AlbumSearchResult(int, SongList)),

src/globalsearch/lastfmsearchprovider.cpp

@@ -23,7 +23,7 @@
 LastFMSearchProvider::LastFMSearchProvider(LastFMService* service, QObject* parent)
   : SimpleSearchProvider(parent),
     service_(service) {
-  Init("Last.fm", "lastfm", QIcon(":last.fm/as.png"), false, false);
+  Init("Last.fm", "lastfm", QIcon(":last.fm/as.png"));
   icon_ = ScaleAndPad(QImage(":last.fm/as.png"));
 
   set_safe_words(QStringList() << "lastfm" << "last.fm");

src/globalsearch/librarysearchprovider.cpp

@@ -33,7 +33,7 @@ LibrarySearchProvider::LibrarySearchProvider(LibraryBackendInterface* backend,
     backend_(backend),
     cover_loader_(new BackgroundThreadImplementation<AlbumCoverLoader, AlbumCoverLoader>(this))
 {
-  Init(name, id, icon, false, true);
+  Init(name, id, icon, WantsSerialisedArtQueries);
 
   cover_loader_->Start(true);
   cover_loader_->Worker()->SetDesiredHeight(kArtHeight);

src/globalsearch/searchprovider.cpp

@@ -25,17 +25,17 @@ const int SearchProvider::kArtHeight = 32;
 
 
 SearchProvider::SearchProvider(QObject* parent)
-  : QObject(parent)
+  : QObject(parent),
+    hints_(0)
 {
 }
 
-void SearchProvider::Init(const QString& name, const QString& id, const QIcon& icon,
-                          bool delay_searches, bool serialised_art) {
+void SearchProvider::Init(const QString& name, const QString& id,
+                          const QIcon& icon, Hints hints) {
   name_ = name;
   id_ = id;
   icon_ = icon;
-  delay_searches_ = delay_searches;
-  serialised_art_ = serialised_art;
+  hints_ = hints;
 }
 
 QStringList SearchProvider::TokenizeQuery(const QString& query) {

src/globalsearch/searchprovider.h

@@ -76,11 +76,34 @@ public:
   };
   typedef QList<Result> ResultList;
 
+  enum Hint {
+    NoHints = 0x00,
+
+    // Indicates that queries to this provider mean making requests to a third
+    // party.  To be polite, queries should be buffered by a few milliseconds
+    // instead of executing them each time the user types a character.
+    WantsDelayedQueries = 0x01,
+
+    // Indicates that this provider wants to be given art queries one after the
+    // other (serially), instead of all at once (in parallel).
+    WantsSerialisedArtQueries = 0x02,
+
+    // Indicates that album cover art is probably going to be loaded remotely.
+    // If a third-party application is making art requests over dbus and has
+    // to get all the art it can before showing results to the user, it might
+    // not load art from this provider.
+    ArtIsProbablyRemote = 0x04
+  };
+  Q_DECLARE_FLAGS(Hints, Hint)
+
   const QString& name() const { return name_; }
   const QString& id() const { return id_; }
   const QIcon& icon() const { return icon_; }
-  const bool wants_delayed_queries() const { return delay_searches_; }
-  const bool wants_serialised_art() const { return serialised_art_; }
+
+  Hints hints() const { return hints_; }
+  bool wants_delayed_queries() const { return hints() & WantsDelayedQueries; }
+  bool wants_serialised_art() const { return hints() & WantsSerialisedArtQueries; }
+  bool art_is_probably_remote() const { return hints() & ArtIsProbablyRemote; }
 
   // Starts a search.  Must emit ResultsAvailable zero or more times and then
   // SearchFinished exactly once, using this ID.
@@ -116,18 +139,18 @@ protected:
 
   // Subclasses must call this from their constructors.
   void Init(const QString& name, const QString& id, const QIcon& icon,
-            bool delay_searches, bool serialised_art);
+            Hints hints = NoHints);
 
 private:
   QString name_;
   QString id_;
   QIcon icon_;
-  bool delay_searches_;
-  bool serialised_art_;
+  Hints hints_;
 };
 
 Q_DECLARE_METATYPE(SearchProvider::Result)
 Q_DECLARE_METATYPE(SearchProvider::ResultList)
+Q_DECLARE_OPERATORS_FOR_FLAGS(SearchProvider::Hints)
 
 
 class BlockingSearchProvider : public SearchProvider {

src/globalsearch/spotifysearchprovider.cpp

@@ -28,7 +28,8 @@ SpotifySearchProvider::SpotifySearchProvider(QObject* parent)
     server_(NULL),
     service_(NULL)
 {
-  Init("Spotify", "spotify", QIcon(":icons/svg/spotify.svg"), true, true);
+  Init("Spotify", "spotify", QIcon(":icons/svg/spotify.svg"),
+       WantsDelayedQueries | WantsSerialisedArtQueries | ArtIsProbablyRemote);
 }
 
 SpotifyServer* SpotifySearchProvider::server() {