[core] Add pause and resume to database filesource implementation

include/mbgl/storage/database_file_source.hpp

@@ -20,6 +20,8 @@ public:
     void forward(const Resource&, const Response&, std::function<void()> callback) override;
     bool canRequest(const Resource&) const override;
     void setProperty(const std::string&, const mapbox::base::Value&) override;
+    void pause() override;
+    void resume() override;
 
     // Methods common to Ambient cache and Offline functionality
 

platform/default/src/mbgl/storage/database_file_source.cpp

@@ -153,6 +153,9 @@ public:
 
     ActorRef<DatabaseFileSourceThread> actor() const { return thread->actor(); }
 
+    void pause() { thread->pause(); }
+    void resume() { thread->resume(); }
+
 private:
     const std::unique_ptr<util::Thread<DatabaseFileSourceThread>> thread;
 };
@@ -277,4 +280,12 @@ void DatabaseFileSource::setProperty(const std::string& key, const mapbox::base:
     }
 }
 
+void DatabaseFileSource::pause() {
+    impl->pause();
+}
+
+void DatabaseFileSource::resume() {
+    impl->resume();
+}
+
 } // namespace mbgl