cc: Remove OutputSurfaceClient::DidSwapBuffers().

cc/output/output_surface_unittest.cc

Index: cc/output/output_surface_unittest.cc
diff --git a/cc/output/output_surface_unittest.cc b/cc/output/output_surface_unittest.cc
index 4f0a1e10f1ecbf84420921c77a724b20acd3c264..d4fa9f7b3fe87e4f9ce27d14526767d111874ed3 100644
--- a/cc/output/output_surface_unittest.cc
+++ b/cc/output/output_surface_unittest.cc
@@ -43,7 +43,6 @@ class TestOutputSurface : public OutputSurface {
                       std::move(software_device)) {}
 
   void SwapBuffers(CompositorFrame frame) override {
-    client_->DidSwapBuffers();
     client_->DidSwapBuffersComplete();
   }
   uint32_t GetFramebufferCopyTextureFormat() override {
@@ -51,8 +50,6 @@ class TestOutputSurface : public OutputSurface {
     return GL_RGB;
   }
 
-  void DidSwapBuffersForTesting() { client_->DidSwapBuffers(); }
-
   void OnSwapBuffersCompleteForTesting() { client_->DidSwapBuffersComplete(); }
 
  protected: