exo: Remove begin frame observer correctly.

components/exo/surface.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 "components/exo/surface.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
@@ skipping 227 matching lines @@
   factory_owner_->surface_ = nullptr;
 
   // Call pending frame callbacks with a null frame time to indicate that they
   // have been cancelled.
   frame_callbacks_.splice(frame_callbacks_.end(), pending_frame_callbacks_);
   active_frame_callbacks_.splice(active_frame_callbacks_.end(),
                                  frame_callbacks_);
   for (const auto& frame_callback : active_frame_callbacks_)
     frame_callback.Run(base::TimeTicks());
 
-  if (begin_frame_source_)
+  if (begin_frame_source_ && needs_begin_frame_)
     begin_frame_source_->RemoveObserver(this);
 
   if (!local_frame_id_.is_null())
     factory_owner_->surface_factory_->Destroy(local_frame_id_);
 
   surface_manager_->UnregisterSurfaceFactoryClient(
       factory_owner_->frame_sink_id_);
 }
 
 // static
@@ skipping 356 matching lines @@
   return value;
 }
 
 void Surface::WillDraw() {
   active_frame_callbacks_.splice(active_frame_callbacks_.end(),
                                  frame_callbacks_);
   UpdateNeedsBeginFrame();
 }
 
 void Surface::SetBeginFrameSource(cc::BeginFrameSource* begin_frame_source) {
+  if (begin_frame_source_ && needs_begin_frame_) {
+    begin_frame_source_->RemoveObserver(this);
+    needs_begin_frame_ = false;
+  }
   begin_frame_source_ = begin_frame_source;
   UpdateNeedsBeginFrame();
 }
 
 void Surface::CheckIfSurfaceHierarchyNeedsCommitToNewSurfaces() {
   if (HasLayerHierarchyChanged())
     SetSurfaceHierarchyNeedsCommitToNewSurfaces();
 }
 
 void Surface::OnLostResources() {
@@ skipping 201 matching lines @@
     solid_quad->SetNew(quad_state, quad_rect, quad_rect, SK_ColorBLACK, false);
   }
 
   frame.render_pass_list.push_back(std::move(render_pass));
 
   factory_owner_->surface_factory_->SubmitCompositorFrame(
       local_frame_id_, std::move(frame), cc::SurfaceFactory::DrawCallback());
 }
 
 void Surface::UpdateNeedsBeginFrame() {
-  if (!begin_frame_source_) {
-    needs_begin_frame_ = false;
+  if (!begin_frame_source_)
     return;
-  }
 
   bool needs_begin_frame = !active_frame_callbacks_.empty();
   if (needs_begin_frame == needs_begin_frame_)
     return;
 
   needs_begin_frame_ = needs_begin_frame;
   if (needs_begin_frame)
     begin_frame_source_->AddObserver(this);
   else
     begin_frame_source_->RemoveObserver(this);
@@ skipping 19 matching lines @@
 
 int64_t Surface::GetPropertyInternal(const void* key,
                                      int64_t default_value) const {
   std::map<const void*, Value>::const_iterator iter = prop_map_.find(key);
   if (iter == prop_map_.end())
     return default_value;
   return iter->second.value;
 }
 
 }  // namespace exo