diff --git a/webrtc/base/logging.h b/webrtc/base/logging.h
index 91d61b3e9..e07045ff1 100644
--- a/webrtc/base/logging.h
+++ b/webrtc/base/logging.h
@@ -246,21 +246,7 @@ void LogMultiline(LoggingSeverity level, const char* label, bool input,
                   const void* data, size_t len, bool hex_mode,
                   LogMultilineState* state);
 
-//////////////////////////////////////////////////////////////////////
-// Macros which automatically disable logging when LOGGING == 0
-//////////////////////////////////////////////////////////////////////
-
-// If LOGGING is not explicitly defined, default to enabled in debug mode
-#if !defined(LOGGING)
-#if defined(_DEBUG) && !defined(NDEBUG)
-#define LOGGING 1
-#else
-#define LOGGING 0
-#endif
-#endif  // !defined(LOGGING)
-
 #ifndef LOG
-#if LOGGING
 
 // The following non-obvious technique for implementation of a
 // conditional log stream was stolen from google3/base/logging.h.
@@ -317,30 +303,6 @@ inline bool LogCheckLevel(LoggingSeverity sev) {
 
 #define LOG_T(sev) LOG(sev) << this << ": "
 
-#else  // !LOGGING
-
-// Hopefully, the compiler will optimize away some of this code.
-// Note: syntax of "1 ? (void)0 : LogMessage" was causing errors in g++,
-//   converted to "while (false)"
-#define LOG(sev) \
-  while (false)rtc:: LogMessage(NULL, 0, rtc::sev).stream()
-#define LOG_V(sev) \
-  while (false) rtc::LogMessage(NULL, 0, sev).stream()
-#define LOG_F(sev) LOG(sev) << __FUNCTION__ << ": "
-#define LOG_CHECK_LEVEL(sev) \
-  false
-#define LOG_CHECK_LEVEL_V(sev) \
-  false
-
-#define LOG_E(sev, ctx, err, ...) \
-  while (false) rtc::LogMessage(__FILE__, __LINE__, rtc::sev, \
-                          rtc::ERRCTX_ ## ctx, err , ##__VA_ARGS__) \
-      .stream()
-
-#define LOG_T(sev) LOG(sev) << this << ": "
-#define LOG_T_F(sev) LOG(sev) << this << ": " << __FUNCTION__ <<
-#endif  // !LOGGING
-
 #define LOG_ERRNO_EX(sev, err) \
   LOG_E(sev, ERRNO, err)
 #define LOG_ERRNO(sev) \
diff --git a/webrtc/base/openssladapter.cc b/webrtc/base/openssladapter.cc
index 601b4afcb..68a1fcb18 100644
--- a/webrtc/base/openssladapter.cc
+++ b/webrtc/base/openssladapter.cc
@@ -695,7 +695,10 @@ bool OpenSSLAdapter::VerifyServerName(SSL* ssl, const char* host,
       }
 
       STACK_OF(CONF_VALUE)* value = meth->i2v(meth, ext_str, NULL);
-      for (int j = 0; j < sk_CONF_VALUE_num(value); ++j) {
+
+      // Cast to size_t to be compilable for both OpenSSL and BoringSSL.
+      for (size_t j = 0; j < static_cast<size_t>(sk_CONF_VALUE_num(value));
+           ++j) {
         CONF_VALUE* nval = sk_CONF_VALUE_value(value, j);
         // The value for nval can contain wildcards
         if (!strcmp(nval->name, "DNS") && string_match(host, nval->value)) {
diff --git a/webrtc/base/thread.cc b/webrtc/base/thread.cc
index 49a299d65..6da9a7fbb 100644
--- a/webrtc/base/thread.cc
+++ b/webrtc/base/thread.cc
@@ -125,6 +125,16 @@ struct ThreadInit {
   Runnable* runnable;
 };
 
+Thread::ScopedDisallowBlockingCalls::ScopedDisallowBlockingCalls()
+  : thread_(Thread::Current()),
+    previous_state_(thread_->SetAllowBlockingCalls(false)) {
+}
+
+Thread::ScopedDisallowBlockingCalls::~ScopedDisallowBlockingCalls() {
+  ASSERT(thread_->IsCurrent());
+  thread_->SetAllowBlockingCalls(previous_state_);
+}
+
 Thread::Thread(SocketServer* ss)
     : MessageQueue(ss),
       priority_(PRIORITY_NORMAL),
@@ -133,7 +143,8 @@ Thread::Thread(SocketServer* ss)
       thread_(NULL),
       thread_id_(0),
 #endif
-      owned_(true) {
+      owned_(true),
+      blocking_calls_allowed_(true) {
   SetName("Thread", this);  // default name
 }
 
@@ -143,6 +154,8 @@ Thread::~Thread() {
 }
 
 bool Thread::SleepMs(int milliseconds) {
+  AssertBlockingIsAllowedOnCurrentThread();
+
 #if defined(WEBRTC_WIN)
   ::Sleep(milliseconds);
   return true;
@@ -276,6 +289,8 @@ bool Thread::Start(Runnable* runnable) {
 }
 
 void Thread::Join() {
+  AssertBlockingIsAllowedOnCurrentThread();
+
   if (running()) {
     ASSERT(!IsCurrent());
 #if defined(WEBRTC_WIN)
@@ -291,6 +306,21 @@ void Thread::Join() {
   }
 }
 
+bool Thread::SetAllowBlockingCalls(bool allow) {
+  ASSERT(IsCurrent());
+  bool previous = blocking_calls_allowed_;
+  blocking_calls_allowed_ = allow;
+  return previous;
+}
+
+// static
+void Thread::AssertBlockingIsAllowedOnCurrentThread() {
+#ifdef _DEBUG
+  Thread* current = Thread::Current();
+  ASSERT(!current || current->blocking_calls_allowed_);
+#endif
+}
+
 #if defined(WEBRTC_WIN)
 // As seen on MSDN.
 // http://msdn.microsoft.com/en-us/library/xcb2z8hs(VS.71).aspx
@@ -357,6 +387,8 @@ void Thread::Stop() {
 }
 
 void Thread::Send(MessageHandler *phandler, uint32 id, MessageData *pdata) {
+  AssertBlockingIsAllowedOnCurrentThread();
+
   if (fStop_)
     return;
 
diff --git a/webrtc/base/thread.h b/webrtc/base/thread.h
index 38727464b..6132aa0a7 100644
--- a/webrtc/base/thread.h
+++ b/webrtc/base/thread.h
@@ -108,6 +108,19 @@ class Thread : public MessageQueue {
 
   static Thread* Current();
 
+  // Used to catch performance regressions. Use this to disallow blocking calls
+  // (Invoke) for a given scope.  If a synchronous call is made while this is in
+  // effect, an assert will be triggered.
+  // Note that this is a single threaded class.
+  class ScopedDisallowBlockingCalls {
+   public:
+    ScopedDisallowBlockingCalls();
+    ~ScopedDisallowBlockingCalls();
+   private:
+    Thread* const thread_;
+    const bool previous_state_;
+  };
+
   bool IsCurrent() const {
     return Current() == this;
   }
@@ -148,8 +161,11 @@ class Thread : public MessageQueue {
   // Uses Send() internally, which blocks the current thread until execution
   // is complete.
   // Ex: bool result = thread.Invoke<bool>(&MyFunctionReturningBool);
+  // NOTE: This function can only be called when synchronous calls are allowed.
+  // See ScopedDisallowBlockingCalls for details.
   template <class ReturnT, class FunctorT>
   ReturnT Invoke(const FunctorT& functor) {
+    AssertBlockingIsAllowedOnCurrentThread();
     FunctorMessageHandler<ReturnT, FunctorT> handler(functor);
     Send(&handler);
     return handler.result();
@@ -212,6 +228,14 @@ class Thread : public MessageQueue {
   // Blocks the calling thread until this thread has terminated.
   void Join();
 
+  // Sets the per-thread allow-blocking-calls flag and returns the previous
+  // value.
+  bool SetAllowBlockingCalls(bool allow);
+
+  static void AssertBlockingIsAllowedOnCurrentThread();
+
+  friend class ScopedDisallowBlockingCalls;
+
  private:
   static void *PreRun(void *pv);
 
@@ -238,6 +262,7 @@ class Thread : public MessageQueue {
 #endif
 
   bool owned_;
+  bool blocking_calls_allowed_;  // By default set to |true|.
 
   friend class ThreadManager;