cc: Set sync token on resource even if context is lost.

cc/resources/resource_provider.cc

 // Copyright 2012 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/resources/resource_provider.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1083 matching lines @@
       target_(resource_provider->BindForSampling(resource_id, unit_, filter)) {}
 
 ResourceProvider::ScopedSamplerGL::~ScopedSamplerGL() {}
 
 ResourceProvider::ScopedWriteLockGL::ScopedWriteLockGL(
     ResourceProvider* resource_provider,
     ResourceId resource_id,
     bool create_mailbox)
     : resource_provider_(resource_provider),
       resource_id_(resource_id),
+      has_sync_token_(false),
       synchronized_(false) {
   DCHECK(thread_checker_.CalledOnValidThread());
   Resource* resource = resource_provider->LockForWrite(resource_id);
   resource_provider_->LazyAllocate(resource);
   if (resource->image_id && resource->dirty_image)
     resource_provider_->BindImageForSampling(resource);
   if (create_mailbox) {
     resource_provider_->CreateMailboxAndBindResource(
         resource_provider_->ContextGL(), resource);
   }
   texture_id_ = resource->gl_id;
   target_ = resource->target;
   format_ = resource->format;
   size_ = resource->size;
   mailbox_ = resource->mailbox();
   sk_color_space_ = resource_provider->GetResourceSkColorSpace(resource);
 }
 
 ResourceProvider::ScopedWriteLockGL::~ScopedWriteLockGL() {
   DCHECK(thread_checker_.CalledOnValidThread());
   Resource* resource = resource_provider_->GetResource(resource_id_);
   DCHECK(resource->locked_for_write);
-  if (sync_token_.HasData())
+  // It's not sufficient to check sync_token_.HasData() here because the sync
+  // might be null because of context loss. Even in that case we want to set the
+  // sync token because it's checked in PrepareSendToParent while drawing.
+  if (has_sync_token_)
     resource->UpdateSyncToken(sync_token_);
   if (synchronized_)
     resource->SetSynchronized();
   resource_provider_->UnlockForWrite(resource);
 }
 
 ResourceProvider::ScopedTextureProvider::ScopedTextureProvider(
     gpu::gles2::GLES2Interface* gl,
     ScopedWriteLockGL* resource_lock,
     bool use_mailbox)
@@ skipping 918 matching lines @@
 
     const int kImportance = 2;
     pmd->CreateSharedGlobalAllocatorDump(guid);
     pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
   }
 
   return true;
 }
 
 }  // namespace cc