cc: Make OutputSurface::Reshape abstract

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 f589a25ff26c2f16e52431e13e27a16cde08eeb6..053f75d4761a905f182e5449328d14325c72dcf1 100644
--- a/cc/output/output_surface_unittest.cc
+++ b/cc/output/output_surface_unittest.cc
@@ -31,6 +31,10 @@ class TestOutputSurface : public OutputSurface {
   void EnsureBackbuffer() override {}
   void DiscardBackbuffer() override {}
   void BindFramebuffer() override {}
+  void Reshape(const gfx::Size& size,
+               float device_scale_factor,
+               const gfx::ColorSpace& color_space,
+               bool has_alpha) override {}
   void SwapBuffers(OutputSurfaceFrame frame) override {
     client_->DidSwapBuffersComplete();
   }