cc: Do bitmap conversion for RasterBuffer in the worker thread.

cc/resources/pixel_buffer_raster_worker_pool.cc

 // 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.
 
 #include "cc/resources/pixel_buffer_raster_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/containers/stack_container.h"
 #include "base/debug/trace_event.h"
@@ skipping 249 matching lines @@
   }
   completed_raster_tasks_.clear();
 }
 
 RasterBuffer* PixelBufferRasterWorkerPool::AcquireBufferForRaster(
     RasterTask* task) {
   DCHECK(std::find_if(raster_task_states_.begin(),
                       raster_task_states_.end(),
                       RasterTaskState::TaskComparator(task)) !=
          raster_task_states_.end());
-  resource_provider_->AcquirePixelRasterBuffer(task->resource()->id());
-  return resource_provider_->MapPixelRasterBuffer(task->resource()->id());
+  return resource_provider_->AcquirePixelRasterBuffer(task->resource()->id());
 }
 
 void PixelBufferRasterWorkerPool::ReleaseBufferForRaster(RasterTask* task) {
   DCHECK(std::find_if(raster_task_states_.begin(),
                       raster_task_states_.end(),
                       RasterTaskState::TaskComparator(task)) !=
          raster_task_states_.end());
   resource_provider_->ReleasePixelRasterBuffer(task->resource()->id());
 }
 
@@ skipping 394 matching lines @@
 
     RasterTaskState::Vector::iterator state_it =
         std::find_if(raster_task_states_.begin(),
                      raster_task_states_.end(),
                      RasterTaskState::TaskComparator(raster_task));
     DCHECK(state_it != raster_task_states_.end());
 
     RasterTaskState& state = *state_it;
     DCHECK_EQ(RasterTaskState::SCHEDULED, state.type);
 
-    // Balanced with MapPixelRasterBuffer() call in AcquireBufferForRaster().
-    bool content_has_changed = resource_provider_->UnmapPixelRasterBuffer(
-        raster_task->resource()->id());
-
     // |content_has_changed| can be false as result of task being canceled or
     // task implementation deciding not to modify bitmap (ie. analysis of raster
     // commands detected content as a solid color).
-    if (!content_has_changed) {
+    if (!raster_task->content_has_changed()) {

[reveman, 2014/08/13 19:19:49]

Let's keep things simple and remove all this conditional "contents have changed"
code from here. This is currently here to avoid an upload when analysis
determined the tile to be solid. We can handle that in BeginSetPixels instead
and avoid an upload at that level. This will make this code much cleaner without
having a real impact on performance.

[auygun, 2014/08/14 10:35:42]

Unittests assume that BeginSetPixels always uploads. Also
PixelBufferRasterWorkerPool still needs to know if any uploads has been
performed since last flush. So I'm adding TryBeginSetPixels which calls
BeginSetPixels if raster bitmap was modified.

[reveman, 2014/08/14 12:26:36]

Can we instead fix the unit tests and have PixelBufferRasterWorkerPool assume
that all BeginSetPixels calls result in an upload? I think that would be much
cleaner. There's already the case that BeginSetPixels might not actually perform
an upload if the context is lost.

[auygun, 2014/08/15 09:20:40]

Done.

       raster_task->WillComplete();
       raster_task->CompleteOnOriginThread(this);
       raster_task->DidComplete();
 
       if (!raster_task->HasFinishedRunning()) {
         // When priorites change, a raster task can be canceled as a result of
         // no longer being of high enough priority to fit in our throttled
         // raster task budget. The task has not yet completed in this case.
         RasterTaskQueue::Item::Vector::const_iterator item_it =
             std::find_if(raster_tasks_.items.begin(),
@@ skipping 48 matching lines @@
 void PixelBufferRasterWorkerPool::ThrottleStateAsValueInto(
     base::debug::TracedValue* throttle_state) const {
   throttle_state->SetInteger("bytes_available_for_upload",
                              max_bytes_pending_upload_ - bytes_pending_upload_);
   throttle_state->SetInteger("bytes_pending_upload", bytes_pending_upload_);
   throttle_state->SetInteger("scheduled_raster_task_count",
                              scheduled_raster_task_count_);
 }
 
 }  // namespace cc