Fix possible loss of data warnings in media_unittests

media/cdm/cenc_utils_unittest.cc

Index: media/cdm/cenc_utils_unittest.cc
diff --git a/media/cdm/cenc_utils_unittest.cc b/media/cdm/cenc_utils_unittest.cc
index beab6edaf2b9fb5a452437f06032020850f3ae91..c124cbd2d21d686473636b8e22f522af38a29593 100644
--- a/media/cdm/cenc_utils_unittest.cc
+++ b/media/cdm/cenc_utils_unittest.cc
@@ -159,9 +159,9 @@ class CencUtilsTest : public testing::Test {
     // and simply appends the data to the end of it. It updates the box size
     // and sets the data size.
     DCHECK(data.size() < 100);
-    pssh_box[3] += data.size();
+    pssh_box[3] += static_cast<uint8_t>(data.size());
     pssh_box.pop_back();
-    pssh_box.push_back(data.size());
+    pssh_box.push_back(static_cast<uint8_t>(data.size()));
     pssh_box.insert(pssh_box.end(), data.begin(), data.end());
   }
 
@@ -284,7 +284,7 @@ TEST_F(CencUtilsTest, PsshBoxLargerThanSize) {
   // Add 20 additional bytes to |box|.
   size_t original_size = box.size();
   for (size_t i = 0; i < 20; ++i)
-    box.push_back(i);
+    box.push_back(static_cast<uint8_t>(i));
 
   // Tries every size greater than |original_size|.
   for (size_t i = original_size + 1; i < box.size(); ++i) {