Un-DCHECK-guard ThreadRestrictionVerifier for strings.

third_party/WebKit/Source/wtf/text/StringImpl.h

Index: third_party/WebKit/Source/wtf/text/StringImpl.h
diff --git a/third_party/WebKit/Source/wtf/text/StringImpl.h b/third_party/WebKit/Source/wtf/text/StringImpl.h
index 97f2c6767bf69b877952e92764be6494d64a0b85..6a9d66c850ef61f88041733a6d782b0dc614fd39 100644
--- a/third_party/WebKit/Source/wtf/text/StringImpl.h
+++ b/third_party/WebKit/Source/wtf/text/StringImpl.h
@@ -35,9 +35,11 @@
 #include <limits.h>
 #include <string.h>
 
-#if DCHECK_IS_ON()
+// TODO(meade): Revert this by 17 Mar 17.
+// This is for investigating crbug.com/694520
+// #if DCHECK_IS_ON()

[sof, 2017/03/10 07:53:33]

Just a suggestion if this is something we do once in a while -- add

 #define CHECK_STRING_THREAD_SAFETY(X) CHECK(X) // DCHECK() once reverted back
to previous.

or something similarly named. With an empty alternative if the check is not
enabled & use it throughout.

[meade_UTC10, 2017/03/13 01:06:08]

I'm not sure if it will be - I'll consider doing that if we find lots of things
when this gets landed.

 #include "wtf/ThreadRestrictionVerifier.h"
-#endif
+// #endif
 
 #if OS(MACOSX)
 typedef const struct __CFString* CFStringRef;
@@ -307,24 +309,30 @@ class WTF_EXPORT StringImpl {
   }
 
   ALWAYS_INLINE bool hasOneRef() const {
-#if DCHECK_IS_ON()
-    DCHECK(isStatic() || m_verifier.isSafeToUse()) << asciiForDebugging();
-#endif
+    // TODO(meade): Revert this by 17 Mar 17.
+    // This is for investigating crbug.com/694520
+    // #if DCHECK_IS_ON()
+    CHECK(isStatic() || m_verifier.isSafeToUse()) << asciiForDebugging();
+    // #endif
     return m_refCount == 1;
   }
 
   ALWAYS_INLINE void ref() const {
-#if DCHECK_IS_ON()
-    DCHECK(isStatic() || m_verifier.onRef(m_refCount)) << asciiForDebugging();
-#endif
+    // TODO(meade): Revert this by 17 Mar 17.
+    // This is for investigating crbug.com/694520
+    // #if DCHECK_IS_ON()
+    CHECK(isStatic() || m_verifier.onRef(m_refCount)) << asciiForDebugging();
+    // #endif
     ++m_refCount;
   }
 
   ALWAYS_INLINE void deref() const {
-#if DCHECK_IS_ON()
-    DCHECK(isStatic() || m_verifier.onDeref(m_refCount))
+    // TODO(meade): Revert this by 17 Mar 17.
+    // This is for investigating crbug.com/694520
+    // #if DCHECK_IS_ON()
+    CHECK(isStatic() || m_verifier.onDeref(m_refCount))
         << asciiForDebugging() << " " << currentThread();
-#endif
+    // #endif
     if (!--m_refCount)
       destroyIfNotStatic();
   }
@@ -511,9 +519,11 @@ class WTF_EXPORT StringImpl {
   void destroyIfNotStatic() const;
   void updateContainsOnlyASCII() const;
 
-#if DCHECK_IS_ON()
+  // TODO(meade): Revert this by 17 Mar 17.
+  // This is for investigating crbug.com/694520
+  // #if DCHECK_IS_ON()
   std::string asciiForDebugging() const;
-#endif
+// #endif
 
 #ifdef STRING_STATS
   static StringStats m_stringStats;
@@ -530,9 +540,11 @@ class WTF_EXPORT StringImpl {
 #endif
 
  private:
-#if DCHECK_IS_ON()
+  // TODO(meade): Revert this by 17 Mar 17.
+  // This is for investigating crbug.com/694520
+  // #if DCHECK_IS_ON()
   mutable ThreadRestrictionVerifier m_verifier;
-#endif
+  // #endif
   mutable unsigned m_refCount;
   const unsigned m_length;
   mutable unsigned m_hash : 24;