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

cc/resources/pixel_buffer_raster_worker_pool.cc

Index: cc/resources/pixel_buffer_raster_worker_pool.cc
diff --git a/cc/resources/pixel_buffer_raster_worker_pool.cc b/cc/resources/pixel_buffer_raster_worker_pool.cc
index 67ae593bde0a5625dc36d2d14a4fd782f442750a..a5ee12f6dfce2a7073121901d9ca60f70150d7a9 100644
--- a/cc/resources/pixel_buffer_raster_worker_pool.cc
+++ b/cc/resources/pixel_buffer_raster_worker_pool.cc
@@ -261,17 +261,16 @@ void PixelBufferRasterWorkerPool::CheckForCompletedTasks() {
   completed_raster_tasks_.clear();
 }
 
-SkCanvas* PixelBufferRasterWorkerPool::AcquireCanvasForRaster(
+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::ReleaseCanvasForRaster(RasterTask* task) {
+void PixelBufferRasterWorkerPool::ReleaseBufferForRaster(RasterTask* task) {
   DCHECK(std::find_if(raster_task_states_.begin(),
                       raster_task_states_.end(),
                       RasterTaskState::TaskComparator(task)) !=
@@ -686,30 +685,21 @@ void PixelBufferRasterWorkerPool::CheckForCompletedRasterizerTasks() {
     RasterTaskState& state = *state_it;
     DCHECK_EQ(RasterTaskState::SCHEDULED, state.type);
 
-    // Balanced with MapPixelRasterBuffer() call in AcquireCanvasForRaster().
-    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->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.
       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(),
-                         raster_tasks_.items.end(),
-                         RasterTaskQueue::Item::TaskComparator(raster_task));
-        if (item_it != raster_tasks_.items.end()) {
-          state.type = RasterTaskState::UNSCHEDULED;
-          continue;
-        }
+      RasterTaskQueue::Item::Vector::const_iterator item_it =
+          std::find_if(raster_tasks_.items.begin(),
+                       raster_tasks_.items.end(),
+                       RasterTaskQueue::Item::TaskComparator(raster_task));
+      if (item_it != raster_tasks_.items.end()) {
+        state.type = RasterTaskState::UNSCHEDULED;
+        continue;
       }
 
       DCHECK(std::find(completed_raster_tasks_.begin(),
@@ -724,8 +714,6 @@ void PixelBufferRasterWorkerPool::CheckForCompletedRasterizerTasks() {
       continue;
     }
 
-    DCHECK(raster_task->HasFinishedRunning());
-
     resource_provider_->BeginSetPixels(raster_task->resource()->id());
     has_performed_uploads_since_last_flush_ = true;