Revert of Add some instrumentation to investigate a possible use afte…

…r free. (patchset chromium#1 id:1 of https://codereview.chromium.org/1254033003/ )

Reason for revert:
This debugging code didn't find any crashes and the original crash reported in BUG 468529 hasn't happened in two months.

Original issue's description:
> Add some instrumentation to investigate a possible use after free.
>
> BUG=468529
> R=rch@chromium.org
>
> Committed: https://crrev.com/cccb61583618f1159fd3f55eeb1ae845078dc077
> Cr-Commit-Position: refs/heads/master@{#341786}

R=rch@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=468529

Review URL: https://codereview.chromium.org/1351673005

Cr-Commit-Position: refs/heads/master@{#349622}

net/quic/quic_http_stream.cc

@@ -5,9 +5,6 @@
 #include "net/quic/quic_http_stream.h"
 
 #include "base/callback_helpers.h"
-#ifdef TEMP_INSTRUMENTATION_468529
-#include "base/debug/alias.h"
-#endif
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
 #include "net/base/io_buffer.h"
@@ -49,16 +46,6 @@ QuicHttpStream::QuicHttpStream(
 }
 
 QuicHttpStream::~QuicHttpStream() {
-#ifdef TEMP_INSTRUMENTATION_468529
-  liveness_ = DEAD;
-  stack_trace_ = base::debug::StackTrace();
-
-  // Probably not necessary, but just in case compiler tries to optimize out the
-  // writes to liveness_ and stack_trace_.
-  base::debug::Alias(&liveness_);
-  base::debug::Alias(&stack_trace_);
-#endif
-
   Close(false);
   if (session_)
     session_->RemoveObserver(this);
@@ -380,8 +367,6 @@ void QuicHttpStream::DoCallback(int rv) {
 
 int QuicHttpStream::DoLoop(int rv) {
   do {
-    CrashIfInvalid();
-
     State state = next_state_;
     next_state_ = STATE_NONE;
     switch (state) {
@@ -564,22 +549,4 @@ void QuicHttpStream::ResetStream() {
     request_body_stream_->Reset();
 }
 
-void QuicHttpStream::CrashIfInvalid() const {
-#ifdef TEMP_INSTRUMENTATION_468529
-  Liveness liveness = liveness_;
-
-  if (liveness == ALIVE)
-    return;
-
-  // Copy relevant variables onto the stack to guarantee they will be available
-  // in minidumps, and then crash.
-  base::debug::StackTrace stack_trace = stack_trace_;
-
-  base::debug::Alias(&liveness);
-  base::debug::Alias(&stack_trace);
-
-  CHECK_EQ(ALIVE, liveness);
-#endif
-}
-
 }  // namespace net

net/quic/quic_http_stream.h

@@ -9,18 +9,6 @@
 
 #include <list>
 
-#include "build/build_config.h"
-
-// TODO(rtenneti): Temporary while investigating crbug.com/468529.
-//                 Note base::Debug::StackTrace() is not supported in NACL
-//                 builds so conditionally disabled it there.
-#ifndef OS_NACL
-#define TEMP_INSTRUMENTATION_468529
-#endif
-
-#ifdef TEMP_INSTRUMENTATION_468529
-#include "base/debug/stack_trace.h"
-#endif
 #include "base/memory/weak_ptr.h"
 #include "net/base/io_buffer.h"
 #include "net/http/http_stream.h"
@@ -87,14 +75,6 @@ class NET_EXPORT_PRIVATE QuicHttpStream
  private:
   friend class test::QuicHttpStreamPeer;
 
-#ifdef TEMP_INSTRUMENTATION_468529
-  // TODO(rtenneti): Temporary while investigating crbug.com/468529
-  enum Liveness {
-    ALIVE = 0xCA11AB13,
-    DEAD = 0xDEADBEEF,
-  };
-#endif
-
   enum State {
     STATE_NONE,
     STATE_SEND_HEADERS,
@@ -128,9 +108,6 @@ class NET_EXPORT_PRIVATE QuicHttpStream
 
   void ResetStream();
 
-  // TODO(rtenneti): Temporary while investigating crbug.com/468529
-  void CrashIfInvalid() const;
-
   State next_state_;
 
   base::WeakPtr<QuicChromiumClientSession> session_;
@@ -186,12 +163,6 @@ class NET_EXPORT_PRIVATE QuicHttpStream
 
   BoundNetLog stream_net_log_;
 
-#ifdef TEMP_INSTRUMENTATION_468529
-  // TODO(rtenneti): Temporary while investigating crbug.com/468529
-  Liveness liveness_ = ALIVE;
-  base::debug::StackTrace stack_trace_;
-#endif
-
   base::WeakPtrFactory<QuicHttpStream> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicHttpStream);