Revert "Revert of https://codereview.chromium.org/112783004/"

This reverts commit 3293fe57a7507541e9040eab880dcd82c43881f4.

Conflicts:
	src/core/SkScaledImageCache.cpp

BUG=

Review URL: https://codereview.chromium.org/108613005

git-svn-id: http://skia.googlecode.com/svn/trunk@12663 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/lazy/SkCachingPixelRef.cpp b/src/lazy/SkCachingPixelRef.cpp
index 667a949..b7eaf57 100644
--- a/src/lazy/SkCachingPixelRef.cpp
+++ b/src/lazy/SkCachingPixelRef.cpp
@@ -90,9 +90,7 @@
 }
 
 void SkCachingPixelRef::onUnlockPixels() {
-    if (fScaledCacheId != NULL) {
-        SkScaledImageCache::Unlock(
-            static_cast<SkScaledImageCache::ID*>(fScaledCacheId));
-        fScaledCacheId = NULL;
-    }
+    SkASSERT(fScaledCacheId != NULL);
+    SkScaledImageCache::Unlock( static_cast<SkScaledImageCache::ID*>(fScaledCacheId));
+    fScaledCacheId = NULL;
 }