Revert "Add start & end markers around |str_stack| for use by Crash service."

This reverts commit 64646172.

Reason for revert: LoggingTest.LogMessageMarkersOnStack is failing on several builders and this test was introduced in this CL:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20Tests%20%28dbg%29%281%29/72386
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20MSan%20Tests/12371

Example error message:
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8932209218566904752/+/steps/base_unittests/0/logs/LoggingTest.LogMessageMarkersOnStack/0


Original change's description:
> Add start & end markers around |str_stack| for use by Crash service.
> 
> Crash can locate particular entries in a stack by scanning for start &
> end markers with unusual values.  We add start & end markers around the
> |str_stack| copy of the LogMessage string, created when we're about to
> crash the process due to a FATAL level log message.
> 
> Bug: 802393
> Change-Id: I8fd462cc515ddbefb8c7b34363eea848171aa776
> Reviewed-on: https://chromium-review.googlesource.com/c/1201344
> Reviewed-by: Wez <wez@chromium.org>
> Reviewed-by: Albert J. Wong <ajwong@chromium.org>
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Commit-Queue: Wez <wez@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#601236}

TBR=ajwong@chromium.org,dcheng@chromium.org,wez@chromium.org

Change-Id: If00343894caa467887191fbb09a4c80233cc94b1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 802393
Reviewed-on: https://chromium-review.googlesource.com/c/1292595Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601295}

base/logging.cc

@@ -8,7 +8,6 @@
 #include <stdint.h>
 
 #include "base/macros.h"
-#include "base/stl_util.h"
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
@@ -832,17 +831,8 @@ LogMessage::~LogMessage() {
       tracker->RecordLogMessage(str_newline);
 
     // Ensure the first characters of the string are on the stack so they
-    // are contained in minidumps for diagnostic purposes. We place start
-    // and end marker values at either end, so we can scan captured stacks
-    // for the data easily.
-    struct {
-      uint32_t start_marker = 0xbedead01;
-      char data[1024];
-      uint32_t end_marker = 0x5050dead;
-    } str_stack;
-    base::strlcpy(str_stack.data, str_newline.data(),
-                  base::size(str_stack.data));
-    base::debug::Alias(&str_stack);
+    // are contained in minidumps for diagnostic purposes.
+    DEBUG_ALIAS_FOR_CSTR(str_stack, str_newline.c_str(), 1024);
 
     if (log_assert_handler_stack.IsCreated() &&
         !log_assert_handler_stack.Get().empty()) {

base/logging_unittest.cc

@@ -829,56 +829,6 @@ TEST_F(LoggingTest, LogPrefix) {
   log_string_ptr = nullptr;
 }
 
-#if !defined(ADDRESS_SANITIZER)
-// Since we scan potentially uninitialized portions of the stack, we can't run
-// this test under address-sanitizer.
-TEST_F(LoggingTest, LogMessageMarkersOnStack) {
-  const uint32_t kLogStartMarker = 0xbedead01;
-  const uint32_t kLogEndMarker = 0x5050dead;
-  const char kTestMessage[] = "Oh noes! I have crashed! 💩";
-
-  uint32_t stack_start = 0;
-
-  // Install a LogAssertHandler which will scan between |stack_start| and its
-  // local-scope stack for the start & end markers, and verify the message.
-  ScopedLogAssertHandler assert_handler(base::BindRepeating(
-      [](uint32_t* stack_start_ptr, const char* file, int line,
-         const base::StringPiece message, const base::StringPiece stack_trace) {
-        uint32_t stack_end;
-        uint32_t* stack_end_ptr = &stack_end;
-
-        // Scan the stack for the expected markers.
-        uint32_t* start_marker = nullptr;
-        uint32_t* end_marker = nullptr;
-        for (uint32_t* ptr = stack_end_ptr; ptr <= stack_start_ptr; ++ptr) {
-          if (*ptr == kLogStartMarker)
-            start_marker = ptr;
-          else if (*ptr == kLogEndMarker)
-            end_marker = ptr;
-        }
-
-        // Verify that start & end markers were found, somewhere, in-between
-        // this and the LogAssertHandler scope, in the LogMessage destructor's
-        // stack frame.
-        ASSERT_TRUE(start_marker);
-        ASSERT_TRUE(end_marker);
-
-        // Verify that the |message| is found in-between the markers.
-        const char* start_char_marker =
-            reinterpret_cast<char*>(start_marker + 1);
-        const char* end_char_marker = reinterpret_cast<char*>(end_marker);
-
-        const base::StringPiece stack_view(start_char_marker,
-                                           end_char_marker - start_char_marker);
-        ASSERT_FALSE(stack_view.find(message) == base::StringPiece::npos);
-      },
-      &stack_start));
-
-  // Trigger a log assertion, with a test message we can check for.
-  LOG(FATAL) << kTestMessage;
-}
-#endif  // !defined(ADDRESS_SANITIZER)
-
 }  // namespace
 
 }  // namespace logging