Implement frame attribution (FrameBlamer)

components/scheduler/base/task_queue.h

Index: components/scheduler/base/task_queue.h
diff --git a/components/scheduler/base/task_queue.h b/components/scheduler/base/task_queue.h
index b20e0777f08362e92b5e2e733c028d1e12e8ef64..11d63b00b5b2f8010d5e0849970a3e67f5260c4a 100644
--- a/components/scheduler/base/task_queue.h
+++ b/components/scheduler/base/task_queue.h
@@ -8,8 +8,15 @@
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
+#include "base/trace_event/trace_event.h"
 #include "components/scheduler/scheduler_export.h"
 
+namespace base {
+namespace debug {
+class BlameContextBase;
+}
+}
+
 namespace scheduler {
 class TimeDomain;
 
@@ -184,6 +191,11 @@ class SCHEDULER_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
   virtual void RemoveTaskObserver(
       base::MessageLoop::TaskObserver* task_observer) = 0;
 
+  // Set the blame context for all tasks executed from this queue.

[chiniforooshan, 2016/03/03 20:39:41]

Shouldn't this be SetBlameContexts (plural) (or AddBlameContext)? I thought a
task could potentially belong to several contexts, no?

[Sami, 2016/03/08 14:36:10]

I've limited a single task queue to only belonging to a single blame context for
simplicity. The tasks themselves can still enter any number of contexts, but we
only support entering one automatically for all tasks.

I've reworded this a bit to make it more obvious.

+  // |blame_context| must be null or outlive this task queue.
+  virtual void SetBlameContext(
+      base::debug::BlameContextBase* blame_context) = 0;
+
   // Removes the task queue from the previous TimeDomain and adds it to
   // |domain|.  This is a moderately expensive operation.
   virtual void SetTimeDomain(TimeDomain* domain) = 0;