[exo]CompositorFrameSinkHolder calls WillDraw in DidReceiveCompositorFrameAck

components/exo/surface_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/surfaces/surface.h"
 #include "base/bind.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/quads/texture_draw_quad.h"
 #include "cc/surfaces/surface_manager.h"
 #include "cc/test/begin_frame_args_test.h"
@@ skipping 311 matching lines @@
   surface->SetBeginFrameSource(&source);
   surface->Attach(buffer.get());
 
   // Request a frame callback so that Surface now needs BeginFrames.
   base::TimeTicks frame_time;
   surface->RequestFrameCallback(
       base::Bind(&SetFrameTime, base::Unretained(&frame_time)));
   surface->Commit();  // Move callback from pending callbacks to current ones.
   RunAllPendingInMessageLoop();
 
-  // Surface should add itself as observer during WillDraw().
-  surface->WillDraw();
+  // Surface should add itself as observer during
+  // DidReceiveCompositorFrameAck().
+  surface->DidReceiveCompositorFrameAck();
   EXPECT_EQ(1u, source.num_observers());
 
   cc::BeginFrameArgs args(source.CreateBeginFrameArgs(BEGINFRAME_FROM_HERE));
   args.frame_time = base::TimeTicks::FromInternalValue(100);
   source.TestOnBeginFrame(args);  // Runs the frame callback.
   EXPECT_EQ(args.frame_time, frame_time);
 
   surface->Commit();  // Acknowledges the BeginFrame.
   RunAllPendingInMessageLoop();
 
   cc::BeginFrameAck expected_ack(args.source_id, args.sequence_number,
                                  args.sequence_number, true);
   EXPECT_EQ(expected_ack, source.LastAckForObserver(surface.get()));
 
   const cc::CompositorFrame& frame = GetFrameFromSurface(surface.get());
   EXPECT_EQ(expected_ack, frame.metadata.begin_frame_ack);
 }
 
 }  // namespace
 }  // namespace exo