Use StopChildProcess instead of base::KillProcess to kill a renderer process

content/public/test/mock_render_process_host.h

Index: content/public/test/mock_render_process_host.h
diff --git a/content/public/test/mock_render_process_host.h b/content/public/test/mock_render_process_host.h
index 81df68607d630ff83f0475bb9b2284ba3078724f..4e39b341f876ee8dce3bebba441e64c111783a7c 100644
--- a/content/public/test/mock_render_process_host.h
+++ b/content/public/test/mock_render_process_host.h
@@ -48,6 +48,7 @@ class MockRenderProcessHost : public RenderProcessHost {
   StoragePartition* GetStoragePartition() const override;
   virtual void AddWord(const base::string16& word);
   bool FastShutdownIfPossible() override;
+  bool FastShutdown(int exit_code, bool wait) override;
   bool FastShutdownStarted() const override;
   void DumpHandles() override;
   base::ProcessHandle GetHandle() const override;