Fix early out in GrResourceCache2::purgeAsNeeded

BUG=chromium:436846
TBR=robertphillips@google.com

Review URL: https://codereview.chromium.org/755193003
diff --git a/src/gpu/GrResourceCache2.h b/src/gpu/GrResourceCache2.h
index 3c5eea5..038e3bc 100644
--- a/src/gpu/GrResourceCache2.h
+++ b/src/gpu/GrResourceCache2.h
@@ -167,7 +167,7 @@
     /// @}
 
     void purgeAsNeeded() {
-        if (fPurging || (fBudgetedCount <= fMaxCount && fBudgetedBytes < fMaxBytes)) {
+        if (fPurging || (fBudgetedCount <= fMaxCount && fBudgetedBytes <= fMaxBytes)) {
             return;
         }
         this->internalPurgeAsNeeded();