TextEditor: get CompletionAssistProvider from editor.

And not from the global object pool. This way, the editors that have
different highlighters for various language dialects, or editors that
support multiple languages in a single editor, can decide themselves on
what CompletionAssistProvider to provide.

Change-Id: Ieebc4a8e7b3de6470fdb8103035aa3b8b2ba6598
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/cpptools/cpptoolseditorsupport.h

@@ -50,6 +50,8 @@ class ITextMark;
 
 namespace CppTools {
 
+class CppCompletionAssistProvider;
+
 /**
  * \brief The CppEditorSupport class oversees the actions that happen when a C++ text editor updates
  *        its document.
@@ -115,6 +117,8 @@ public:
     /// \param force do not check if the old semantic info is still valid
     void recalculateSemanticInfoDetached(bool force = false);
 
+    CppCompletionAssistProvider *completionAssistProvider() const;
+
 signals:
     void documentUpdated();
     void diagnosticsChanged();
@@ -189,6 +193,9 @@ private:
     unsigned m_lastHighlightRevision;
     QFuture<TextEditor::HighlightingResult> m_highlighter;
     QScopedPointer<CppTools::CppHighlightingSupport> m_highlightingSupport;
+
+    // Completion:
+    QScopedPointer<CppCompletionAssistProvider> m_completionAssistProvider;
 };
 
 } // namespace CppTools