Revert "Add instrumentation to investigate a possible UAF."

This reverts commit 68ddeefb.

Reason for revert: crbug.com/901501 has been merged to crbug.com/986211, which is fixed.

Original change's description:
> Add instrumentation to investigate a possible UAF.
>
> Bug: 901501
> Change-Id: Ic778c96c1bb10a9f4bb2f8f3efd883e452bc9742
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1606770
> Auto-Submit: Zhongyi Shi <zhongyi@chromium.org>
> Commit-Queue: Ryan Hamilton <rch@chromium.org>
> Reviewed-by: Ryan Hamilton <rch@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#658861}

TBR=rch@chromium.org,zhongyi@chromium.org

Bug: 901501
Change-Id: I84096ef16edfd37210a7c02f4c1c523dd5d76c57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1856724Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Commit-Queue: Ryan Hamilton <rch@chromium.org>
Auto-Submit: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705246}

net/spdy/spdy_http_stream.cc

@@ -10,9 +10,6 @@
 #include <utility>
 
 #include "base/bind.h"
-#ifdef TEMP_INSTRUMENTATION_901501
-#include "base/debug/alias.h"
-#endif
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ -130,14 +127,6 @@ SpdyHttpStream::~SpdyHttpStream() {
     stream_->DetachDelegate();
     DCHECK(!stream_);
   }
-#ifdef TEMP_INSTRUMENTATION_901501
-  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
 }
 
 int SpdyHttpStream::InitializeStream(const HttpRequestInfo* request_info,
@@ -455,8 +444,7 @@ void SpdyHttpStream::OnDataSent() {
 void SpdyHttpStream::OnTrailers(const spdy::SpdyHeaderBlock& trailers) {}
 
 void SpdyHttpStream::OnClose(int status) {
-  CHECK(stream_);
-  CrashIfInvalid();
+  DCHECK(stream_);
 
   // Cancel any pending reads from the upload data stream.
   if (request_info_ && request_info_->upload_data_stream)
@@ -480,8 +468,6 @@ void SpdyHttpStream::OnClose(int status) {
       return;
   }
 
-  CrashIfInvalid();
-
   if (status == OK) {
     // We need to complete any pending buffered read now.
     DoBufferedReadCallback();
@@ -489,8 +475,6 @@ void SpdyHttpStream::OnClose(int status) {
       return;
   }
 
-  CrashIfInvalid();
-
   if (!response_callback_.is_null()) {
     DoResponseCallback(status);
   }
@@ -607,8 +591,6 @@ bool SpdyHttpStream::ShouldWaitForMoreBufferedData() const {
 }
 
 void SpdyHttpStream::DoBufferedReadCallback() {
-  CrashIfInvalid();
-
   buffered_read_callback_pending_ = false;
 
   // If the transaction is cancelled or errored out, we don't need to complete
@@ -630,8 +612,6 @@ void SpdyHttpStream::DoBufferedReadCallback() {
   if (!user_buffer_.get())
     return;
 
-  CrashIfInvalid();
-
   if (!response_body_queue_.IsEmpty()) {
     int rv =
         response_body_queue_.Dequeue(user_buffer_->data(), user_buffer_len_);
@@ -694,22 +674,4 @@ void SpdyHttpStream::SetPriority(RequestPriority priority) {
   }
 }
 
-void SpdyHttpStream::CrashIfInvalid() const {
-#ifdef TEMP_INSTRUMENTATION_901501
-  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/spdy/spdy_http_stream.h

@@ -10,13 +10,6 @@
 #include <list>
 #include <memory>
 
-#include "build/build_config.h"
-
-// TODO(zhongyi): Temporary while investigating http://crbug.com/901501.
-#ifndef OS_NACL
-#define TEMP_INSTRUMENTATION_901501
-#include "base/debug/stack_trace.h"
-#endif
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ -103,14 +96,6 @@ class NET_EXPORT_PRIVATE SpdyHttpStream : public SpdyStream::Delegate,
   NetLogSource source_dependency() const override;
 
  private:
-#ifdef TEMP_INSTRUMENTATION_901501
-  // TODO(zhongyi): Temporary while investigating http://crbug.com/901501.
-  enum Liveness {
-    ALIVE = 0xCA11AB13,
-    DEAD = 0xDEADBEEF,
-  };
-#endif
-
   // Helper function used to initialize private members and to set delegate on
   // stream when stream is created.
   void InitializeStreamHelper();
@@ -151,9 +136,6 @@ class NET_EXPORT_PRIVATE SpdyHttpStream : public SpdyStream::Delegate,
   void DoBufferedReadCallback();
   bool ShouldWaitForMoreBufferedData() const;
 
-  // TODO(zhongyi): Temporary while investigating http://crbug.com/901501.
-  void CrashIfInvalid() const;
-
   const base::WeakPtr<SpdySession> spdy_session_;
 
   // The ID of the pushed stream if one is claimed by this request.
@@ -227,12 +209,6 @@ class NET_EXPORT_PRIVATE SpdyHttpStream : public SpdyStream::Delegate,
 
   bool was_alpn_negotiated_;
 
-#ifdef TEMP_INSTRUMENTATION_901501
-  // TODO(zhongyi): Temporary while investigating http://crbug.com/901501.
-  Liveness liveness_ = ALIVE;
-  base::debug::StackTrace stack_trace_;
-#endif
-
   base::WeakPtrFactory<SpdyHttpStream> weak_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(SpdyHttpStream);