Disable VP8 encoder HW acceleration on NVidia devices.

NVidia HW encoder bitrate control is allowing too much
bitrate fluctuation. Plus average encoding time is not enough
for 720p 30 fps support.

R=wzh@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/48099004

Cr-Commit-Position: refs/heads/master@{#9014}
diff --git a/talk/app/webrtc/java/src/org/webrtc/MediaCodecVideoEncoder.java b/talk/app/webrtc/java/src/org/webrtc/MediaCodecVideoEncoder.java
index d28ff10..d481d19 100644
--- a/talk/app/webrtc/java/src/org/webrtc/MediaCodecVideoEncoder.java
+++ b/talk/app/webrtc/java/src/org/webrtc/MediaCodecVideoEncoder.java
@@ -66,7 +66,7 @@
   private static final String H264_MIME_TYPE = "video/avc";
   // List of supported HW VP8 codecs.
   private static final String[] supportedVp8HwCodecPrefixes =
-    {"OMX.qcom.", "OMX.Nvidia.", "OMX.Intel." };
+    {"OMX.qcom.", "OMX.Intel." };
   // List of supported HW H.264 codecs.
   private static final String[] supportedH264HwCodecPrefixes =
     {"OMX.qcom." };