Revert of TaskGraphRunner Group support

cc/raster/task_graph_work_queue.cc

Index: cc/raster/task_graph_work_queue.cc
diff --git a/cc/raster/task_graph_work_queue.cc b/cc/raster/task_graph_work_queue.cc
index 95faedca4b7065becd8198d02fcf95e2070d490f..655a005b024804117fc9052a16ca20dd523868ca 100644
--- a/cc/raster/task_graph_work_queue.cc
+++ b/cc/raster/task_graph_work_queue.cc
@@ -5,41 +5,11 @@
 #include "cc/raster/task_graph_work_queue.h"
 
 #include <algorithm>
-#include <map>
 #include <utility>
 
 #include "base/trace_event/trace_event.h"
 
 namespace cc {
-namespace {
-
-bool CompareTaskPriority(const TaskGraphWorkQueue::PrioritizedTask& a,
-                         const TaskGraphWorkQueue::PrioritizedTask& b) {
-  // In this system, numerically lower priority is run first.
-  return a.priority > b.priority;
-}
-
-class CompareTaskNamespacePriority {
- public:
-  explicit CompareTaskNamespacePriority(uint16_t category)
-      : category_(category) {}
-
-  bool operator()(const TaskGraphWorkQueue::TaskNamespace* a,
-                  const TaskGraphWorkQueue::TaskNamespace* b) {
-    DCHECK(!a->ready_to_run_tasks.at(category_).empty());
-    DCHECK(!b->ready_to_run_tasks.at(category_).empty());
-
-    // Compare based on task priority of the ready_to_run_tasks heap .front()
-    // will hold the max element of the heap, except after pop_heap, when max
-    // element is moved to .back().
-    return CompareTaskPriority(a->ready_to_run_tasks.at(category_).front(),
-                               b->ready_to_run_tasks.at(category_).front());
-  }
-
- private:
-  uint16_t category_;
-};
-}  // namespace
 
 TaskGraphWorkQueue::TaskNamespace::TaskNamespace() {}
 
@@ -67,9 +37,7 @@
   }
 
   // Build new "ready to run" queue and remove nodes from old graph.
-  for (auto& ready_to_run_tasks_it : task_namespace.ready_to_run_tasks) {
-    ready_to_run_tasks_it.second.clear();
-  }
+  task_namespace.ready_to_run_tasks.clear();
   for (const TaskGraph::Node& node : graph->nodes) {
     // Remove any old nodes that are associated with this task. The result is
     // that the old graph is left with all nodes not present in this graph,
@@ -98,17 +66,14 @@
                   node.task) != task_namespace.running_tasks.end())
       continue;
 
-    task_namespace.ready_to_run_tasks[node.category].push_back(PrioritizedTask(
-        node.task, &task_namespace, node.category, node.priority));
-  }
-
-  // Rearrange the elements in each vector within |ready_to_run_tasks| in such a
-  // way that they form a heap.
-  for (auto& it : task_namespace.ready_to_run_tasks) {
-    auto& ready_to_run_tasks = it.second;
-    std::make_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
-                   CompareTaskPriority);
-  }
+    task_namespace.ready_to_run_tasks.push_back(
+        PrioritizedTask(node.task, &task_namespace, node.priority));
+  }
+
+  // Rearrange the elements in |ready_to_run_tasks| in such a way that they
+  // form a heap.
+  std::make_heap(task_namespace.ready_to_run_tasks.begin(),
+                 task_namespace.ready_to_run_tasks.end(), CompareTaskPriority);
 
   // Swap task graph.
   task_namespace.graph.Swap(graph);
@@ -135,59 +100,41 @@
   }
 
   // Build new "ready to run" task namespaces queue.
-  for (auto& ready_to_run_namespaces_it : ready_to_run_namespaces_) {
-    ready_to_run_namespaces_it.second.clear();
-  }
-  for (auto& namespace_it : namespaces_) {
-    auto& task_namespace = namespace_it.second;
-    for (auto& ready_to_run_tasks_it : task_namespace.ready_to_run_tasks) {
-      auto& ready_to_run_tasks = ready_to_run_tasks_it.second;
-      uint16_t category = ready_to_run_tasks_it.first;
-      if (!ready_to_run_tasks.empty()) {
-        ready_to_run_namespaces_[category].push_back(&task_namespace);
-      }
-    }
+  ready_to_run_namespaces_.clear();
+  for (auto& it : namespaces_) {
+    if (!it.second.ready_to_run_tasks.empty())
+      ready_to_run_namespaces_.push_back(&it.second);
   }
 
   // Rearrange the task namespaces in |ready_to_run_namespaces| in such a
   // way that they form a heap.
-  for (auto& it : ready_to_run_namespaces_) {
-    uint16_t category = it.first;
-    auto& task_namespace = it.second;
-    std::make_heap(task_namespace.begin(), task_namespace.end(),
-                   CompareTaskNamespacePriority(category));
-  }
-}
-
-TaskGraphWorkQueue::PrioritizedTask TaskGraphWorkQueue::GetNextTaskToRun(
-    uint16_t category) {
-  TaskNamespace::Vector& ready_to_run_namespaces =
-      ready_to_run_namespaces_[category];
-  DCHECK(!ready_to_run_namespaces.empty());
-
-  // Take top priority TaskNamespace from |ready_to_run_namespaces|.
-  std::pop_heap(ready_to_run_namespaces.begin(), ready_to_run_namespaces.end(),
-                CompareTaskNamespacePriority(category));
-  TaskNamespace* task_namespace = ready_to_run_namespaces.back();
-  ready_to_run_namespaces.pop_back();
-
-  PrioritizedTask::Vector& ready_to_run_tasks =
-      task_namespace->ready_to_run_tasks[category];
-  DCHECK(!ready_to_run_tasks.empty());
+  std::make_heap(ready_to_run_namespaces_.begin(),
+                 ready_to_run_namespaces_.end(), CompareTaskNamespacePriority);
+}
+
+TaskGraphWorkQueue::PrioritizedTask TaskGraphWorkQueue::GetNextTaskToRun() {
+  DCHECK(!ready_to_run_namespaces_.empty());
+
+  // Take top priority TaskNamespace from |ready_to_run_namespaces_|.
+  std::pop_heap(ready_to_run_namespaces_.begin(),
+                ready_to_run_namespaces_.end(), CompareTaskNamespacePriority);
+  TaskNamespace* task_namespace = ready_to_run_namespaces_.back();
+  ready_to_run_namespaces_.pop_back();
+  DCHECK(!task_namespace->ready_to_run_tasks.empty());
 
   // Take top priority task from |ready_to_run_tasks|.
-  std::pop_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
-                CompareTaskPriority);
-  PrioritizedTask task = ready_to_run_tasks.back();
-  ready_to_run_tasks.pop_back();
-
-  // Add task namespace back to |ready_to_run_namespaces| if not empty after
+  std::pop_heap(task_namespace->ready_to_run_tasks.begin(),
+                task_namespace->ready_to_run_tasks.end(), CompareTaskPriority);
+  PrioritizedTask task = task_namespace->ready_to_run_tasks.back();
+  task_namespace->ready_to_run_tasks.pop_back();
+
+  // Add task namespace back to |ready_to_run_namespaces_| if not empty after
   // taking top priority task.
-  if (!ready_to_run_tasks.empty()) {
-    ready_to_run_namespaces.push_back(task_namespace);
-    std::push_heap(ready_to_run_namespaces.begin(),
-                   ready_to_run_namespaces.end(),
-                   CompareTaskNamespacePriority(category));
+  if (!task_namespace->ready_to_run_tasks.empty()) {
+    ready_to_run_namespaces_.push_back(task_namespace);
+    std::push_heap(ready_to_run_namespaces_.begin(),
+                   ready_to_run_namespaces_.end(),
+                   CompareTaskNamespacePriority);
   }
 
   // Add task to |running_tasks|.
@@ -217,26 +164,19 @@
     dependent_node.dependencies--;
     // Task is ready if it has no dependencies. Add it to |ready_to_run_tasks_|.
     if (!dependent_node.dependencies) {
-      PrioritizedTask::Vector& ready_to_run_tasks =
-          task_namespace->ready_to_run_tasks[dependent_node.category];
-
-      bool was_empty = ready_to_run_tasks.empty();
-      ready_to_run_tasks.push_back(
-          PrioritizedTask(dependent_node.task, task_namespace,
-                          dependent_node.category, dependent_node.priority));
-      std::push_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
+      bool was_empty = task_namespace->ready_to_run_tasks.empty();
+      task_namespace->ready_to_run_tasks.push_back(PrioritizedTask(
+          dependent_node.task, task_namespace, dependent_node.priority));
+      std::push_heap(task_namespace->ready_to_run_tasks.begin(),
+                     task_namespace->ready_to_run_tasks.end(),
                      CompareTaskPriority);
-
       // Task namespace is ready if it has at least one ready to run task. Add
       // it to |ready_to_run_namespaces_| if it just become ready.
       if (was_empty) {
-        TaskNamespace::Vector& ready_to_run_namespaces =
-            ready_to_run_namespaces_[dependent_node.category];
-
-        DCHECK(std::find(ready_to_run_namespaces.begin(),
-                         ready_to_run_namespaces.end(),
-                         task_namespace) == ready_to_run_namespaces.end());
-        ready_to_run_namespaces.push_back(task_namespace);
+        DCHECK(std::find(ready_to_run_namespaces_.begin(),
+                         ready_to_run_namespaces_.end(),
+                         task_namespace) == ready_to_run_namespaces_.end());
+        ready_to_run_namespaces_.push_back(task_namespace);
       }
       ready_to_run_namespaces_has_heap_properties = false;
     }
@@ -245,13 +185,9 @@
   // Rearrange the task namespaces in |ready_to_run_namespaces_| in such a way
   // that they yet again form a heap.
   if (!ready_to_run_namespaces_has_heap_properties) {
-    for (auto& it : ready_to_run_namespaces_) {
-      uint16_t category = it.first;
-      auto& ready_to_run_namespaces = it.second;
-      std::make_heap(ready_to_run_namespaces.begin(),
-                     ready_to_run_namespaces.end(),
-                     CompareTaskNamespacePriority(category));
-    }
+    std::make_heap(ready_to_run_namespaces_.begin(),
+                   ready_to_run_namespaces_.end(),
+                   CompareTaskNamespacePriority);
   }
 
   // Finally add task to |completed_tasks_|.
@@ -273,7 +209,7 @@
 
   // Remove namespace if finished running tasks.
   DCHECK_EQ(0u, task_namespace.completed_tasks.size());
-  DCHECK(!HasReadyToRunTasksInNamespace(&task_namespace));
+  DCHECK_EQ(0u, task_namespace.ready_to_run_tasks.size());
   DCHECK_EQ(0u, task_namespace.running_tasks.size());
   namespaces_.erase(it);
 }