cc: Get rid of SurfaceDestroyed and use SurfaceDiscarded instead

cc/surfaces/display_scheduler.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/display_scheduler.h"
 
 #include <vector>
 
 #include "base/auto_reset.h"
 #include "base/stl_util.h"
@@ skipping 119 matching lines @@
   bool pending_surfaces_changed = false;
   if (display_damaged || valid_ack)
     pending_surfaces_changed = UpdateHasPendingSurfaces();
 
   if (display_damaged || pending_surfaces_changed)
     ScheduleBeginFrameDeadline();
 }
 
 void DisplayScheduler::SurfaceCreated(const SurfaceInfo& surface_info) {
   SurfaceId surface_id = surface_info.id();
   DCHECK(!base::ContainsKey(surface_states_, surface_id));

[Eric Seckler, 2017/06/02 12:01:16]

Hm, and it looks like this is no longer necessarily true. Probably need to get
rid of the DCHECK (and maybe replace it with a comment).

The DCHECK is triggered here:
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.mac%2...

Log snippet:
[ RUN      ] ExtensionApiTabTest.Tabs2
[...]
[15112:771:0601/152703.002830:FATAL:display_scheduler.cc(140)] Check failed:
!base::ContainsKey(surface_states_, surface_id).
0   browser_tests                       0x000000010524bc2c
base::debug::StackTrace::StackTrace(unsigned long) + 28
1   browser_tests                       0x00000001052710b0
logging::LogMessage::~LogMessage() + 224
2   browser_tests                       0x00000001079c31a8
cc::DisplayScheduler::SurfaceCreated(cc::SurfaceInfo const&) + 152
3   browser_tests                       0x00000001079e0683
cc::SurfaceManager::SurfaceCreated(cc::SurfaceInfo const&) + 275
4   browser_tests                       0x00000001079be331
cc::CompositorFrameSinkSupport::OnSurfaceActivated(cc::Surface*) + 241

   surface_states_[surface_id] = SurfaceBeginFrameState();
 }
 
-void DisplayScheduler::SurfaceDestroyed(const SurfaceId& surface_id) {
+void DisplayScheduler::SurfaceDiscarded(const SurfaceId& surface_id) {
   auto it = surface_states_.find(surface_id);
   if (it == surface_states_.end())
     return;
   surface_states_.erase(it);
   if (UpdateHasPendingSurfaces())
     ScheduleBeginFrameDeadline();
 }
 
 void DisplayScheduler::SurfaceDamageExpected(const SurfaceId& surface_id,
                                              const BeginFrameArgs& args) {
@@ skipping 272 matching lines @@
 }
 
 void DisplayScheduler::DidReceiveSwapBuffersAck() {
   uint32_t swap_id = next_swap_id_ - pending_swaps_;
   pending_swaps_--;
   TRACE_EVENT_ASYNC_END0("cc", "DisplayScheduler:pending_swaps", swap_id);
   ScheduleBeginFrameDeadline();
 }
 
 }  // namespace cc