Delay activation/draw on GPU tile work completion

cc/raster/one_copy_raster_buffer_provider.cc

 // Copyright 2014 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/raster/one_copy_raster_buffer_provider.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <limits>
 #include <utility>
 
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/histograms.h"
 #include "cc/base/math_util.h"
 #include "cc/resources/platform_color.h"
 #include "cc/resources/resource_format.h"
 #include "cc/resources/resource_util.h"
 #include "cc/resources/scoped_resource.h"
 #include "gpu/GLES2/gl2extchromium.h"
+#include "gpu/command_buffer/client/context_support.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 #include "ui/gfx/buffer_format_util.h"
 
 namespace cc {
 namespace {
 
 // 4MiB is the size of 4 512x512 tiles, which has proven to be a good
 // default batch size for copy operations.
 const int kMaxBytesPerCopyOperation = 1024 * 1024 * 4;
@@ skipping 121 matching lines @@
   return ResourceFormatRequiresSwizzle(GetResourceFormat(must_support_alpha));
 }
 
 bool OneCopyRasterBufferProvider::CanPartialRasterIntoProvidedResource() const {
   // While OneCopyRasterBufferProvider has an internal partial raster
   // implementation, it cannot directly partial raster into the externally
   // owned resource provided in AcquireBufferForRaster.
   return false;
 }
 
+uint64_t OneCopyRasterBufferProvider::SetReadyToDrawCallback(
+    const ResourceProvider::ResourceIdArray& resource_ids,
+    const base::Callback<void(uint64_t)>& callback,
+    uint64_t pending_callback_id) const {
+  if (!async_worker_context_enabled_)
+    return 0;
+
+  gpu::SyncToken sync_token =
+      resource_provider_->GetSyncTokenForResources(resource_ids);
+  uint64_t callback_id = sync_token.release_count();
+  DCHECK_NE(callback_id, 0u);
+
+  if (callback_id != pending_callback_id) {

[vmpstr, 2016/12/07 21:00:25]

Can you add a comment explaining what's going on here?

+    compositor_context_provider_->ContextSupport()->SignalSyncToken(
+        sync_token, base::Bind(callback, callback_id));
+  }
+
+  return callback_id;
+}
+
 void OneCopyRasterBufferProvider::Shutdown() {
   staging_pool_.Shutdown();
   pending_raster_buffers_.clear();
 }
 
 void OneCopyRasterBufferProvider::PlaybackAndCopyOnWorkerThread(
     const Resource* resource,
     ResourceProvider::ScopedWriteLockGL* resource_lock,
     const gpu::SyncToken& sync_token,
     const RasterSource* raster_source,
@@ skipping 211 matching lines @@
   resource_lock->set_synchronized(!async_worker_context_enabled_);
 }
 
 gfx::BufferUsage OneCopyRasterBufferProvider::StagingBufferUsage() const {
   return use_partial_raster_
              ? gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT
              : gfx::BufferUsage::GPU_READ_CPU_READ_WRITE;
 }
 
 }  // namespace cc