Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I080090d50f1a368a4e7c1a0732297bb6a295e34f
diff --git a/libs/hwui/utils/TestWindowContext.cpp b/libs/hwui/utils/TestWindowContext.cpp
index c885491..eba6769 100644
--- a/libs/hwui/utils/TestWindowContext.cpp
+++ b/libs/hwui/utils/TestWindowContext.cpp
@@ -58,7 +58,7 @@
 
 public:
 
-    TestWindowData(SkISize size) : mSize(size) {
+    explicit TestWindowData(SkISize size) : mSize(size) {
         android::BufferQueue::createBufferQueue(&mProducer, &mConsumer);
         mCpuConsumer = new android::CpuConsumer(mConsumer, 1);
         mCpuConsumer->setName(android::String8("TestWindowContext"));