Cheaper thread-safe atomic initialization of static references.

Source/web/WebImageCache.cpp

Index: Source/web/WebImageCache.cpp
diff --git a/Source/web/WebImageCache.cpp b/Source/web/WebImageCache.cpp
index 33350464183a3d4970fb5d8f90709ff81e15786f..8648b1e225d7af5c39c645cbf97fb54f9c06d616 100644
--- a/Source/web/WebImageCache.cpp
+++ b/Source/web/WebImageCache.cpp
@@ -37,23 +37,22 @@ namespace blink {
 
 void WebImageCache::setCacheLimitInBytes(size_t size)
 {
-    ImageDecodingStore::instance()->setCacheLimitInBytes(size);
+    ImageDecodingStore::instance().setCacheLimitInBytes(size);
 }
 
 void WebImageCache::clear()
 {
-    if (ImageDecodingStore::instance())
-        ImageDecodingStore::instance()->clear();
+    ImageDecodingStore::instance().clear();
 }
 
 size_t WebImageCache::memoryUsageInBytes()
 {
-    return ImageDecodingStore::instance()->memoryUsageInBytes();
+    return ImageDecodingStore::instance().memoryUsageInBytes();
 }
 
 unsigned WebImageCache::cacheEntries()
 {
-    return ImageDecodingStore::instance()->cacheEntries();
+    return ImageDecodingStore::instance().cacheEntries();
 }
 
 }  // namespace blink