Fix valgrind issue in SkBase64Test.cpp

https://codereview.chromium.org/152153002/



git-svn-id: http://skia.googlecode.com/svn/trunk@13276 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/SkBase64Test.cpp b/tests/SkBase64Test.cpp
index aba9691..217e2ca 100644
--- a/tests/SkBase64Test.cpp
+++ b/tests/SkBase64Test.cpp
@@ -11,15 +11,16 @@
 
 DEF_TEST(SkBase64Test, reporter) {
     char all[256];
-    for (int index = 0; index < 256; index++) {
+    for (int index = 0; index < 256; ++index) {
         all[index] = (signed char) (index + 1);
     }
 
-    for (int offset = 0; offset < 6; offset++) {
+    for (int offset = 0; offset < 6; ++offset) {
         size_t length = 256 - offset;
         size_t encodeLength = SkBase64::Encode(all + offset, length, NULL);
         SkAutoTMalloc<char> src(encodeLength + 1);
         SkBase64::Encode(all + offset, length, src.get());
+        src[encodeLength] = '\0';
         SkBase64 tryMe;
         tryMe.decode(src.get(), encodeLength);
         REPORTER_ASSERT(reporter, (strcmp((const char*) (all + offset), tryMe.getData()) == 0));