cc: Clean up PBRWP::ScheduleTasks a bit.

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 48e6f9a114b58e34743c5396e66b16b91602a081..a7d9b31e1ec573b7140f14b836e9cae4905b0820 100644
--- a/cc/resources/pixel_buffer_raster_worker_pool.cc
+++ b/cc/resources/pixel_buffer_raster_worker_pool.cc
@@ -148,6 +148,8 @@ void PixelBufferRasterWorkerPool::ScheduleTasks(RasterTask::Queue* queue) {
   should_notify_client_if_no_tasks_are_pending_ = true;
   should_notify_client_if_no_tasks_required_for_activation_are_pending_ = true;
 
+  tasks_required_for_activation_.clear();
+
   // Build new pixel buffer task set.
   TaskMap new_pixel_buffer_tasks;
   for (RasterTaskVector::const_iterator it = raster_tasks().begin();
@@ -156,15 +158,11 @@ void PixelBufferRasterWorkerPool::ScheduleTasks(RasterTask::Queue* queue) {
     DCHECK(new_pixel_buffer_tasks.find(task) == new_pixel_buffer_tasks.end());
     DCHECK(!task->HasCompleted());
 
-    // Use existing pixel buffer task if available.
-    TaskMap::iterator pixel_buffer_it = pixel_buffer_tasks_.find(task);
-    if (pixel_buffer_it == pixel_buffer_tasks_.end()) {
-      new_pixel_buffer_tasks[task] = NULL;
-      continue;
-    }
-
-    new_pixel_buffer_tasks[task] = pixel_buffer_it->second;
+    new_pixel_buffer_tasks[task] = pixel_buffer_tasks_[task];
     pixel_buffer_tasks_.erase(task);
+
+    if (IsRasterTaskRequiredForActivation(task))
+      tasks_required_for_activation_.insert(task);
   }
 
   // Transfer remaining pixel buffer tasks to |new_pixel_buffer_tasks|
@@ -184,22 +182,17 @@ void PixelBufferRasterWorkerPool::ScheduleTasks(RasterTask::Queue* queue) {
                        completed_tasks_.end(),
                        task) == completed_tasks_.end());
       completed_tasks_.push_back(task);
-    }
-  }
-
-  tasks_required_for_activation_.clear();
-  for (TaskMap::iterator it = new_pixel_buffer_tasks.begin();
-       it != new_pixel_buffer_tasks.end(); ++it) {
-    internal::RasterWorkerPoolTask* task = it->first;
-    if (IsRasterTaskRequiredForActivation(task))
+    } else if (IsRasterTaskRequiredForActivation(task)) {
       tasks_required_for_activation_.insert(task);
+    }
   }
 
   // |tasks_required_for_activation_| contains all tasks that need to
   // complete before we can send a "ready to activate" signal. Tasks
   // that have already completed should not be part of this set.
   for (TaskDeque::const_iterator it = completed_tasks_.begin();
-       it != completed_tasks_.end(); ++it) {
+       it != completed_tasks_.end() && !tasks_required_for_activation_.empty();
+       ++it) {
     tasks_required_for_activation_.erase(*it);
   }