Delay activation/draw on GPU tile work completion

cc/raster/raster_buffer_provider.h

 // Copyright 2013 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.
 
 #ifndef CC_RASTER_RASTER_BUFFER_PROVIDER_H_
 #define CC_RASTER_RASTER_BUFFER_PROVIDER_H_
 
 #include <stddef.h>
 
 #include "cc/playback/raster_source.h"
 #include "cc/raster/raster_buffer.h"
 #include "cc/raster/task_graph_runner.h"
 #include "cc/raster/tile_task.h"
 #include "cc/resources/resource_format.h"
+#include "cc/resources/resource_provider.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace cc {
 class Resource;
 
 class CC_EXPORT RasterBufferProvider {
  public:
   RasterBufferProvider();
   virtual ~RasterBufferProvider();
@@ skipping 31 matching lines @@
   // Returns the format to use for the tiles.
   virtual ResourceFormat GetResourceFormat(bool must_support_alpha) const = 0;
 
   // Determine if the resource requires swizzling.
   virtual bool IsResourceSwizzleRequired(bool must_support_alpha) const = 0;
 
   // Determine if the RasterBufferProvider can handle partial raster into
   // the Resource provided in AcquireBufferForRaster.
   virtual bool CanPartialRasterIntoProvidedResource() const = 0;
 
+  // Returns true if the indicated resource is ready to draw.
+  virtual bool IsResourceReadyToDraw(ResourceId id) const = 0;
+
+  // Calls the provided |callback| when the provided |resources| are ready to
+  // draw. Returns a callback ID which can be used to track this callback.
+  // Will return 0 if no callback is needed (resources are already ready to
+  // draw). The caller may optionally pass the ID of a pending callback to
+  // avoid creating a new callback unnecessarily.

[vmpstr, 2017/01/05 22:00:46]

Can you specify to pass 0 if no pending callback exists? Also, is this something
that the RasterBufferProvider (or its overrides) can keep track of? That is, it
should know the last callback id it returned, no?

Or is there something more subtle here?

[ericrk, 2017/01/09 23:05:21]

The RasterBufferProvider knows the last callback it returned, but the
TileManager simultaneously requests callbacks for both ready to draw and ready
to activate callbacks - RasterBufferProvider doesn't know the difference between
these so it can't really de-dupe them.

+  virtual uint64_t SetReadyToDrawCallback(
+      const ResourceProvider::ResourceIdArray& resource_ids,
+      const base::Callback<void()>& callback,
+      uint64_t pending_callback_id) const = 0;
+
   // Shutdown for doing cleanup.
   virtual void Shutdown() = 0;
 
  protected:
   // Check if resource format matches output format.
   static bool ResourceFormatRequiresSwizzle(ResourceFormat format);
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_RASTER_BUFFER_PROVIDER_H_