[Merge to M57] Scheduler: Enqueue non-JS-timer tasks into the unthrottled task runner

third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp

Index: third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
diff --git a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
index c7f578b378db1da39959338cce06ad95dc3d395a..07ec73d4aef5010d116f323138dcb70903728809 100644
--- a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
+++ b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
@@ -16,6 +16,18 @@ namespace blink {
 RefPtr<WebTaskRunner> TaskRunnerHelper::get(TaskType type, LocalFrame* frame) {
   // TODO(haraken): Optimize the mapping from TaskTypes to task runners.
   switch (type) {
+    case TaskType::Timer:
+      return frame ? frame->frameScheduler()->timerTaskRunner()
+                   : Platform::current()->currentThread()->getWebTaskRunner();
+    case TaskType::UnspecedLoading:
+    case TaskType::Networking:
+      return frame ? frame->frameScheduler()->loadingTaskRunner()
+                   : Platform::current()->currentThread()->getWebTaskRunner();
+    // Throttling following tasks may break existing web pages, so tentatively
+    // these are unthrottled.
+    // TODO(nhiroki): Throttle them again after we're convinced that it's safe
+    // or provide a mechanism that web pages can opt-out it if throttling is not
+    // desirable.
     case TaskType::DOMManipulation:
     case TaskType::UserInteraction:
     case TaskType::HistoryTraversal:
@@ -31,15 +43,8 @@ RefPtr<WebTaskRunner> TaskRunnerHelper::get(TaskType type, LocalFrame* frame) {
     case TaskType::DatabaseAccess:
     case TaskType::Presentation:
     case TaskType::Sensor:
-    case TaskType::Timer:
     case TaskType::UnspecedTimer:
     case TaskType::MiscPlatformAPI:
-      return frame ? frame->frameScheduler()->timerTaskRunner()
-                   : Platform::current()->currentThread()->getWebTaskRunner();
-    case TaskType::UnspecedLoading:
-    case TaskType::Networking:
-      return frame ? frame->frameScheduler()->loadingTaskRunner()
-                   : Platform::current()->currentThread()->getWebTaskRunner();
     case TaskType::Unthrottled:
       return frame ? frame->frameScheduler()->unthrottledTaskRunner()
                    : Platform::current()->currentThread()->getWebTaskRunner();