WebDataConsumerHandle shouldn't be used on non-Oilpan threads.

public/platform/WebDataConsumerHandle.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebDataConsumerHandle_h
 #define WebDataConsumerHandle_h
 
 #include <stddef.h>
 
 #if INSIDE_BLINK
 #include "wtf/PassOwnPtr.h"
 #endif
 
 #include "public/platform/WebCommon.h"
 
 namespace blink {
 
 // WebDataConsumerHandle represents the "consumer" side of a data pipe. A user
 // can read data from it.
 //
 // A WebDataConsumerHandle is a thread-safe object. A user can call
 // |obtainReader| or destruct the object on any thread.
 // A WebDataConsumerHandle having a reader is called "locked". A
 // WebDataConsumerHandle or its reader are called "waiting" when reading from
 // the handle or reader returns ShouldWait.
+//
+// WebDataConsumerHandle can be created / used / destructed only on
+// Oilpan-enabled threads.
+// TODO(yhirano): Remove this restriction.
 class BLINK_PLATFORM_EXPORT WebDataConsumerHandle {
 public:
     using Flags = unsigned;
     static const Flags FlagNone = 0;
 
     enum Result {
         Ok,
         Done,
         Busy,
         ShouldWait,
@@ skipping 57 matching lines @@
 
         // Ends a two-phase read.
         // |readSize| indicates the actual read size.
         virtual Result endRead(size_t readSize)
         {
             BLINK_ASSERT_NOT_REACHED();
             return UnexpectedError;
         }
     };
 
-    virtual ~WebDataConsumerHandle() { }
+    WebDataConsumerHandle();
+    virtual ~WebDataConsumerHandle();
 
     // Returns a non-null reader. This function can be called only when this
     // handle is not locked. |client| can be null. Otherwise, |*client| must be
     // valid as long as the reader is valid. The returned reader is bound to
     // the calling thread and client notification will be called on the thread
     // if |client| is not null.
     // If |client| is not null and the handle is not waiting, client
     // notification is called asynchronously.
 #if INSIDE_BLINK
-    PassOwnPtr<Reader> obtainReader(Client* client) { return adoptPtr(obtainReaderInternal(client)); }
+    PassOwnPtr<Reader> obtainReader(Client*);
 #endif
 
     // Returns a string literal (e.g. class name) for debugging only.
     virtual const char* debugName() const { return "WebDataConsumerHandle"; }
 
 private:
     // The caller takes ownership of the returned object.
     virtual Reader* obtainReaderInternal(Client* client)
     {
         BLINK_ASSERT_NOT_REACHED();
         return nullptr;
     }
 };
 
 } // namespace blink
 
 #endif // WebDataConsumerHandle_h