media: use size_t for integer iterator to Vector::size()

Change-Id: I0a744dc7815a86a993df9b0623440be620ec8903
diff --git a/drm/common/DrmSupportInfo.cpp b/drm/common/DrmSupportInfo.cpp
index 5400bdd..584c6a6 100644
--- a/drm/common/DrmSupportInfo.cpp
+++ b/drm/common/DrmSupportInfo.cpp
@@ -47,7 +47,7 @@
         return false;
     }
 
-    for (unsigned int i = 0; i < mMimeTypeVector.size(); i++) {
+    for (size_t i = 0; i < mMimeTypeVector.size(); i++) {
         const String8 item = mMimeTypeVector.itemAt(i);
 
         if (!strcasecmp(item.string(), mimeType.string())) {
@@ -58,7 +58,7 @@
 }
 
 bool DrmSupportInfo::isSupportedFileSuffix(const String8& fileType) const {
-    for (unsigned int i = 0; i < mFileSuffixVector.size(); i++) {
+    for (size_t i = 0; i < mFileSuffixVector.size(); i++) {
         const String8 item = mFileSuffixVector.itemAt(i);
 
         if (!strcasecmp(item.string(), fileType.string())) {