Use per-frame TaskRunner instead of thread's default in DataConsumerHandle

third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp

Index: third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp b/third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp
index 8b335d42f85c5b98c7573833af61f6d1e61c465a..867030fcb3168e808059809031358409f4a4800c 100644
--- a/third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp
+++ b/third_party/WebKit/Source/modules/fetch/DataConsumerTee.cpp
@@ -6,6 +6,7 @@
 
 #include "core/dom/ActiveDOMObject.h"
 #include "core/dom/ExecutionContext.h"
+#include "core/dom/TaskRunnerHelper.h"
 #include "modules/fetch/DataConsumerHandleUtil.h"
 #include "modules/fetch/FetchBlobDataConsumerHandle.h"
 #include "platform/CrossThreadFunctional.h"
@@ -183,9 +184,9 @@ public:
                 // No client is registered.
                 return;
             }
-            DCHECK(m_readerThread);
-            if (!m_readerThread->isCurrentThread()) {
-                m_readerThread->getWebTaskRunner()->postTask(BLINK_FROM_HERE, crossThreadBind(&DestinationContext::notify, wrapPassRefPtr(this)));
+            DCHECK(m_readerTaskRunner);
+            if (!m_readerTaskRunner->runsTasksOnCurrentThread()) {
+                m_readerTaskRunner->postTask(BLINK_FROM_HERE, crossThreadBind(&DestinationContext::notify, wrapPassRefPtr(this)));
                 return;
             }
         }
@@ -200,15 +201,15 @@ public:
     // caller.
     void attachReader(WebDataConsumerHandle::Client* client)
     {
-        DCHECK(!m_readerThread);
+        DCHECK(!m_readerTaskRunner);
         DCHECK(!m_client);
-        m_readerThread = Platform::current()->currentThread();
+        m_readerTaskRunner = client->getTaskRunner()->clone();
         m_client = client;
     }
     void detachReader()
     {
-        DCHECK(m_readerThread && m_readerThread->isCurrentThread());
-        m_readerThread = nullptr;
+        DCHECK(m_readerTaskRunner && m_readerTaskRunner->runsTasksOnCurrentThread());
+        m_readerTaskRunner = nullptr;
         m_client = nullptr;
     }
     const std::unique_ptr<Vector<char>>& top() const { return m_queue.first(); }
@@ -231,7 +232,7 @@ public:
 private:
     DestinationContext()
         : m_result(WebDataConsumerHandle::ShouldWait)
-        , m_readerThread(nullptr)
+        , m_readerTaskRunner(nullptr)
         , m_client(nullptr)
         , m_offset(0)
         , m_isTwoPhaseReadInProgress(false)
@@ -242,19 +243,13 @@ private:
     {
         MutexLocker locker(m_mutex);
         DCHECK(!m_client);
-        DCHECK(!m_readerThread);
+        DCHECK(!m_readerTaskRunner);
         m_queue.clear();
     }
 
     Result m_result;
     Deque<std::unique_ptr<Vector<char>>> m_queue;
-    // Note: Holding a WebThread raw pointer is not generally safe, but we can
-    // do that in this case because:
-    //  1. Destructing a ReaderImpl when the bound thread ends is a user's
-    //     responsibility.
-    //  2. |m_readerThread| will never be used after the associated reader is
-    //     detached.
-    WebThread* m_readerThread;
+    std::unique_ptr<WebTaskRunner> m_readerTaskRunner;

[haraken, 2016/07/28 09:19:30]

Instead of holding a task runner, can we probably use m_client->getTaskRunner()?

[tzik, 2016/07/28 14:45:34]

Done.

     WebDataConsumerHandle::Client* m_client;
     size_t m_offset;
     bool m_isTwoPhaseReadInProgress;
@@ -269,10 +264,7 @@ public:
         MutexLocker locker(context()->mutex());
         context()->attachReader(client);
         if (client) {
-            // We need to use crossThreadBind here to retain the context. Note
-            // |context()| return value is of type DestinationContext*, not
-            // PassRefPtr<DestinationContext>.
-            Platform::current()->currentThread()->getWebTaskRunner()->postTask(BLINK_FROM_HERE, crossThreadBind(&DestinationContext::notify, wrapPassRefPtr(context())));
+            client->getTaskRunner()->postTask(BLINK_FROM_HERE, bind(&DestinationContext::notify, wrapPassRefPtr(context())));
         }
     }
     ~DestinationReader() override
@@ -373,6 +365,11 @@ public:
         stopInternal();
     }
 
+    WebTaskRunner* getTaskRunner() override
+    {
+        return TaskRunnerHelper::getUnthrottledTaskRunner(getExecutionContext());
+    }
+
     void stop() override
     {
         stopInternal();