Revert of TaskGraphRunner Group support

content/renderer/raster_worker_pool.cc

Index: content/renderer/raster_worker_pool.cc
diff --git a/content/renderer/raster_worker_pool.cc b/content/renderer/raster_worker_pool.cc
index ddeb57dfc709f60c9240ae0b402fcdb16dd5bc65..89ed6d62b91c65a83fe32912336df4cdf8ebd4d4 100644
--- a/content/renderer/raster_worker_pool.cc
+++ b/content/renderer/raster_worker_pool.cc
@@ -3,8 +3,6 @@
 // found in the LICENSE file.
 
 #include "content/renderer/raster_worker_pool.h"
-
-#include <utility>
 
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_restrictions.h"
@@ -49,8 +47,7 @@
       if (!graph_.nodes.empty())
         dependencies = 1;
 
-      cc::TaskGraph::Node node(graph_task.get(), 0u /* category */,
-                               0u /* priority */, dependencies);
+      cc::TaskGraph::Node node(graph_task.get(), 0, dependencies);
       if (dependencies) {
         graph_.edges.push_back(
             cc::TaskGraph::Edge(graph_.nodes.back().task, node.task));
@@ -151,9 +148,7 @@
   tasks_.push_back(make_scoped_refptr(new ClosureTask(task)));
   graph_.Reset();
   for (const auto& graph_task : tasks_)
-    graph_.nodes.push_back(
-        cc::TaskGraph::Node(graph_task.get(), 0u /* category */,
-                            0u /* priority */, 0u /* dependencies */));
+    graph_.nodes.push_back(cc::TaskGraph::Node(graph_task.get(), 0, 0));
 
   ScheduleTasksWithLockAcquired(namespace_token_, &graph_);
   completed_tasks_.clear();
@@ -169,7 +164,7 @@
   base::AutoLock lock(lock_);
 
   while (true) {
-    if (!RunTaskWithLockAcquired()) {
+    if (!work_queue_.HasReadyToRunTasks()) {
       // Exit when shutdown is set and no more tasks are pending.
       if (shutdown_)
         break;
@@ -178,6 +173,8 @@
       has_ready_to_run_tasks_cv_.Wait();
       continue;
     }
+
+    RunTaskWithLockAcquired();
   }
 }
 
@@ -261,28 +258,12 @@
   work_queue_.CollectCompletedTasks(token, completed_tasks);
 }
 
-bool RasterWorkerPool::RunTaskWithLockAcquired() {
+void RasterWorkerPool::RunTaskWithLockAcquired() {
   TRACE_EVENT0("toplevel", "TaskGraphRunner::RunTask");
 
   lock_.AssertAcquired();
 
-  // Find the first category with any tasks to run. This task graph runner
-  // treats categories as an additional priority.
-  // TODO(ericrk): Add more category/thread logic.
-  const auto& ready_to_run_namespaces = work_queue_.ready_to_run_namespaces();
-  auto found = std::find_if(
-      ready_to_run_namespaces.cbegin(), ready_to_run_namespaces.cend(),
-      [](const std::pair<uint16_t,
-                         cc::TaskGraphWorkQueue::TaskNamespace::Vector>& pair) {
-        return !pair.second.empty();
-      });
-
-  if (found == ready_to_run_namespaces.cend()) {
-    return false;
-  }
-
-  const uint16_t category = found->first;
-  auto prioritized_task = work_queue_.GetNextTaskToRun(category);
+  auto prioritized_task = work_queue_.GetNextTaskToRun();
   cc::Task* task = prioritized_task.task;
 
   // There may be more work available, so wake up another worker thread.
@@ -307,8 +288,6 @@
   if (work_queue_.HasFinishedRunningTasksInNamespace(
           prioritized_task.task_namespace))
     has_namespaces_with_finished_running_tasks_cv_.Broadcast();
-
-  return true;
 }
 
 RasterWorkerPool::ClosureTask::ClosureTask(const base::Closure& closure)