avoid GCC content::CacheStorage::kSizeUnknown redeclaration error

content/browser/cache_storage/cache_storage_index.h

Index: content/browser/cache_storage/cache_storage_index.h
diff --git a/content/browser/cache_storage/cache_storage_index.h b/content/browser/cache_storage/cache_storage_index.h
index 3665ec6e7de95d8a2a1a8f9a46cf4bfb00154d1e..0f6c5a1946b24ba2e19ac4452b8627692b530ff6 100644
--- a/content/browser/cache_storage/cache_storage_index.h
+++ b/content/browser/cache_storage/cache_storage_index.h
@@ -25,7 +25,7 @@ class CONTENT_EXPORT CacheStorageIndex {
     CacheMetadata(const std::string& name, int64_t size)
         : name(name), size(size) {}
     std::string name;
-    // The size (in bytes) of the cache. Set to CacheStorage::kSizeUnknown if
+    // The size (in bytes) of the cache. Set to kCacheStorageSizeUnknown if
     // size not known.
     int64_t size;
   };
@@ -43,7 +43,7 @@ class CONTENT_EXPORT CacheStorageIndex {
   bool SetCacheSize(const std::string& cache_name, int64_t size);
 
   // Return the size (in bytes) of the specified cache. Will return
-  // CacheStorage::kSizeUnknown if the specified cache does not exist.
+  // kCacheStorageSizeUnknown if the specified cache does not exist.
   int64_t GetCacheSize(const std::string& cache_name) const;
 
   const std::list<CacheMetadata>& ordered_cache_metadata() const {
@@ -78,7 +78,7 @@ class CONTENT_EXPORT CacheStorageIndex {
       cache_metadata_map_;
 
   // The total size of all caches in this store.
-  int64_t storage_size_ = CacheStorage::kSizeUnknown;
+  int64_t storage_size_ = kCacheStorageSizeUnknown;
 
   // The doomed cache metadata saved when calling DoomCache.
   CacheMetadata doomed_cache_metadata_;