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 f1ea1ac8812b6c4040cbe0708da612cce243d1d6..4fb1c65060423bb053e3e5cf18096f1c2e5dcd48 100644
--- a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
+++ b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.cpp
@@ -25,7 +25,6 @@ RefPtr<WebTaskRunner> TaskRunnerHelper::get(TaskType type, LocalFrame* frame) {
     case TaskType::RemoteEvent:
     case TaskType::WebSocket:
     case TaskType::Microtask:
-    case TaskType::PostedMessage:
     case TaskType::UnshippedPortMessage:
     case TaskType::FileReading:
     case TaskType::DatabaseAccess:
@@ -41,6 +40,12 @@ RefPtr<WebTaskRunner> TaskRunnerHelper::get(TaskType type, LocalFrame* frame) {
     case TaskType::Networking:
       return frame ? frame->frameScheduler()->loadingTaskRunner()
                    : Platform::current()->currentThread()->getWebTaskRunner();
+    // We found throttling PostedMessage tasks may break existing web pages, so
+    // tentatively make it unthrottled.
+    // TODO(nhiroki): Consider to throttle this again maybe after making a
+    // mechanism that web pages can opt-out the throttling if throttling is not
+    // desirable.
+    case TaskType::PostedMessage:

[nhiroki, 2017/02/02 05:46:38]

As my comment on the issue[1], I'm still not sure why we move only PostedMessage
to the unthrottled task runner for a short-term fix. Why don't we move other
task types (other than Timer/UnspecedTimer) to the unthrottled task runner until
we have a mechanism to opt-out throttling from web pages or something else?

[1] https://bugs.chromium.org/p/chromium/issues/detail?id=684947#c18

[altimin, 2017/02/02 18:41:25]

+1, I'm particularly interested in unthrottling WebSocket messages.

[Sami, 2017/02/02 23:37:10]

Yeah, this seems like a reasonable step for now. If these other tasks are a
problem for CPU usage, we'll eventually find out once we improve our CPU
profiling and other metrics.

[nhiroki, 2017/02/03 15:07:34]

Acknowledged.

[nhiroki, 2017/02/03 15:07:34]

Acknowledged.

     case TaskType::Unthrottled:
       return frame ? frame->frameScheduler()->unthrottledTaskRunner()
                    : Platform::current()->currentThread()->getWebTaskRunner();