Cleanup namespace ending comment

(This is a merge of http://go/wvgerrit/13400 from the Widevine CDM
repository.)

Replace "};  // namespace" with "}  // namespace":
ag -l --ignore-dir third_party "};  //" | \
while read f; do sed -r -i 's/\};  \/\//}  \/\//' $f ; done

Replace "// unnamed namespace" with "// namespace":
ag -l --ignore-dir third_party "unnamed namespace" | \
while read f; do sed -r -i 's/unnamed namespace/namespace/' $f ; done

Change-Id: I50ece9a127ce669f15cd532dfae1dd741338a075

libwvdrmengine/cdm/core/src/cdm_engine.cpp

@@ -21,7 +21,7 @@
 namespace {
 const uint32_t kUpdateUsageInformationPeriod = 60;  // seconds
 const size_t kUsageReportsPerRequest = 1;
-}  // unnamed namespace
+}  // namespace
 
 namespace wvcdm {