overview: Add API to remove search providers

As extensions are now expected to provide a "disable" function,
they need to remove search providers they added. Implement the
removal functionality and add a public removeSearchProvider()
method.

https://bugzilla.gnome.org/show_bug.cgi?id=657548

js/ui/overview.js

@@ -237,6 +237,10 @@ Overview.prototype = {
         this._viewSelector.addSearchProvider(provider);
     },
 
+    removeSearchProvider: function(provider) {
+        this._viewSelector.removeSearchProvider(provider);
+    },
+
     setMessage: function(text, undoCallback, undoLabel) {
         if (this.isDummy)
             return;

js/ui/search.js

@@ -356,6 +356,14 @@ SearchSystem.prototype = {
         this._providers.push(provider);
     },
 
+    unregisterProvider: function (provider) {
+        let index = this._providers.indexOf(provider);
+        if (index == -1)
+            return;
+        provider.searchSystem = null;
+        this._providers.splice(index, 1);
+    },
+
     getProviders: function() {
         return this._providers;
     },

js/ui/searchDisplay.js

@@ -294,11 +294,23 @@ SearchResults.prototype = {
         }
         resultDisplayBin.set_child(resultDisplay.actor);
 
-        this._providerMeta.push({ actor: providerBox,
+        this._providerMeta.push({ provider: provider,
+                                  actor: providerBox,
                                   resultDisplay: resultDisplay });
         this._content.add(providerBox);
     },
 
+    destroyProviderMeta: function(provider) {
+        for (let i=0; i < this._providerMeta.length; i++) {
+            let meta = this._providerMeta[i];
+            if (meta.provider == provider) {
+                meta.actor.destroy();
+                this._providerMeta.splice(i, 1);
+                break;
+            }
+        }
+    },
+
     _clearDisplay: function() {
         this._selectedProvider = -1;
         this._visibleResultsCount = 0;

js/ui/viewSelector.js

@@ -210,6 +210,11 @@ SearchTab.prototype = {
         this._searchResults.createProviderMeta(provider);
     },
 
+    removeSearchProvider: function(provider) {
+        this._searchSystem.unregisterProvider(provider);
+        this._searchResults.destroyProviderMeta(provider);
+    },
+
     startSearch: function(event) {
         global.stage.set_key_focus(this._text);
         this._text.event(event, false);
@@ -563,6 +568,10 @@ ViewSelector.prototype = {
 
     addSearchProvider: function(provider) {
         this._searchTab.addSearchProvider(provider);
+    },
+
+    removeSearchProvider: function(provider) {
+        this._searchTab.removeSearchProvider(provider);
     }
 };
 Signals.addSignalMethods(ViewSelector.prototype);