Enable VP9 support for Widevine key system.

chrome/common/chrome_content_client.cc

Index: chrome/common/chrome_content_client.cc
diff --git a/chrome/common/chrome_content_client.cc b/chrome/common/chrome_content_client.cc
index 26e24ce8b8f3626dc7152c8072cf00de0f8aec9d..aa2e42da1ce25b09c6fd0e1522cdfaa7ebde3241 100644
--- a/chrome/common/chrome_content_client.cc
+++ b/chrome/common/chrome_content_client.cc
@@ -279,8 +279,7 @@ void ComputeBuiltInPlugins(std::vector<content::PepperPluginInfo>* plugins) {
       std::vector<std::string> codecs;
       codecs.push_back(kCdmSupportedCodecVorbis);
       codecs.push_back(kCdmSupportedCodecVp8);
-      // TODO(xhwang): Add VP9 when it's supported by Widevine CDM.
-      // See http://crbug.com/361318
+      codecs.push_back(kCdmSupportedCodecVp9);
 #if defined(USE_PROPRIETARY_CODECS)
 // TODO(ddorwin): Rename these macros to reflect their real meaning: whether the
 // CDM Chrome was built [and shipped] with support these types.