[Logging] Hint of use-after-free indicating error in POSIX's LockImpl.

Error 22 (EINVAL) is often associated with use-after-frees.
I've seen multiple developers independently spending cycles figuring
this out. Add a hint for everyone once and for all in POSIX's LockImpl

Issues where this may be useful:
https://bugs.chromium.org/p/chromium/issues/list?q=%22Check+failed%3A+rv+%3D%3D+0+(22+vs.+0)%22

Sadly I couldn't find a way to test this. I tried to write a death
test on a manual use-after-free but the error is unreliable.

R=dcheng@chromium.org

Bug: 818163
Change-Id: I2f9a3aeadebd8bd7b32e2a28d1ba4b801efed9ff
Reviewed-on: https://chromium-review.googlesource.com/1040586Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556593}

base/synchronization/lock_impl_posix.cc

@@ -4,9 +4,12 @@
 
 #include "base/synchronization/lock_impl.h"
 
-#include <string.h>
+#include <string>
 
 #include "base/debug/activity_tracker.h"
+#include "base/logging.h"
+#include "base/posix/safe_strerror.h"
+#include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/synchronization_buildflags.h"
 #include "build/build_config.h"
@@ -14,6 +17,30 @@
 namespace base {
 namespace internal {
 
+namespace {
+
+#if DCHECK_IS_ON()
+const char* AdditionalHintForSystemErrorCode(int error_code) {
+  switch (error_code) {
+    case EINVAL:
+      return "Hint: This is often related to a use-after-free.";
+    default:
+      return "";
+  }
+}
+#endif  // DCHECK_IS_ON()
+
+std::string SystemErrorCodeToString(int error_code) {
+#if DCHECK_IS_ON()
+  return base::safe_strerror(error_code) + ". " +
+         AdditionalHintForSystemErrorCode(error_code);
+#else   // DCHECK_IS_ON()
+  return std::string();
+#endif  // DCHECK_IS_ON()
+}
+
+}  // namespace
+
 // Determines which platforms can consider using priority inheritance locks. Use
 // this define for platform code that may not compile if priority inheritance
 // locks aren't available. For this platform code,
@@ -30,32 +57,32 @@ namespace internal {
 LockImpl::LockImpl() {
   pthread_mutexattr_t mta;
   int rv = pthread_mutexattr_init(&mta);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
 #if PRIORITY_INHERITANCE_LOCKS_POSSIBLE()
   if (PriorityInheritanceAvailable()) {
     rv = pthread_mutexattr_setprotocol(&mta, PTHREAD_PRIO_INHERIT);
-    DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+    DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
   }
 #endif
 #ifndef NDEBUG
   // In debug, setup attributes for lock error checking.
   rv = pthread_mutexattr_settype(&mta, PTHREAD_MUTEX_ERRORCHECK);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
 #endif
   rv = pthread_mutex_init(&native_handle_, &mta);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
   rv = pthread_mutexattr_destroy(&mta);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
 }
 
 LockImpl::~LockImpl() {
   int rv = pthread_mutex_destroy(&native_handle_);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
 }
 
 bool LockImpl::Try() {
   int rv = pthread_mutex_trylock(&native_handle_);
-  DCHECK(rv == 0 || rv == EBUSY) << ". " << strerror(rv);
+  DCHECK(rv == 0 || rv == EBUSY) << ". " << SystemErrorCodeToString(rv);
   return rv == 0;
 }
 
@@ -73,7 +100,7 @@ void LockImpl::Lock() {
 
   base::debug::ScopedLockAcquireActivity lock_activity(this);
   int rv = pthread_mutex_lock(&native_handle_);
-  DCHECK_EQ(rv, 0) << ". " << strerror(rv);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
 }
 
 // static