avoid GCC content::CacheStorage::kSizeUnknown redeclaration error

content/browser/cache_storage/cache_storage_cache.cc

Index: content/browser/cache_storage/cache_storage_cache.cc
diff --git a/content/browser/cache_storage/cache_storage_cache.cc b/content/browser/cache_storage/cache_storage_cache.cc
index e84e4f473e8d2063c9f55da4ef28640b4eac069c..59f161efd7465ff1159b1115ed249c1c2d8e8fdf 100644
--- a/content/browser/cache_storage/cache_storage_cache.cc
+++ b/content/browser/cache_storage/cache_storage_cache.cc
@@ -1190,7 +1190,7 @@ void CacheStorageCache::UpdateCacheSize() {
 void CacheStorageCache::UpdateCacheSizeGotSize(
     std::unique_ptr<CacheStorageCacheHandle> cache_handle,
     int current_cache_size) {
-  DCHECK_NE(current_cache_size, CacheStorage::kSizeUnknown);
+  DCHECK_NE(current_cache_size, kCacheStorageSizeUnknown);
   int64_t old_cache_size = cache_size_;
   cache_size_ = current_cache_size;
 
@@ -1390,7 +1390,7 @@ void CacheStorageCache::InitGotCacheSize(const base::Closure& callback,
   // (which is why the size was calculated), or 2) it must match the current
   // size. If the sizes aren't equal then there is a bug in how the cache size
   // is saved in the store's index.
-  if (cache_size_ != CacheStorage::kSizeUnknown && cache_size_ != cache_size) {
+  if (cache_size_ != kCacheStorageSizeUnknown && cache_size_ != cache_size) {
     // TODO(cmumford): Add UMA for this.
     LOG(ERROR) << "Cache size/index mismatch";
     DCHECK_EQ(cache_size_, cache_size);