New equality operators, for structs related to webrtc::VideoCodec.

Added for the structs VideoCodecVP8, VideoCodecVP9, VideoCodecH264,
and SpatialLayer.

New operators are used to replace memcmp in VCMEncoderDataBase. Using
memcmp to compare structs is generally unreliable, since the struct
may contain random padding bytes due to alignment requirements
(affects at least VideoCodecH264). And in the case of VideoCodecVP8,
we need to exclude the tl_factory pointers from the comparison.

Bug: webrtc:8830
Change-Id: I40432ea7834e288f8c89ce0a28a630ae1800dff8
Reviewed-on: https://webrtc-review.googlesource.com/62761
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22500}
diff --git a/modules/video_coding/encoder_database.cc b/modules/video_coding/encoder_database.cc
index 80716df..a514e14 100644
--- a/modules/video_coding/encoder_database.cc
+++ b/modules/video_coding/encoder_database.cc
@@ -138,23 +138,23 @@
 
   switch (new_send_codec.codecType) {
     case kVideoCodecVP8:
-      if (memcmp(&new_send_codec.VP8(), send_codec_.VP8(),
-                 sizeof(new_send_codec.VP8())) != 0) {
+      if (new_send_codec.VP8() != *send_codec_.VP8()) {
         return true;
       }
       break;
+
     case kVideoCodecVP9:
-      if (memcmp(&new_send_codec.VP9(), send_codec_.VP9(),
-                 sizeof(new_send_codec.VP9())) != 0) {
+      if (new_send_codec.VP9() != *send_codec_.VP9()) {
         return true;
       }
       break;
+
     case kVideoCodecH264:
-      if (memcmp(&new_send_codec.H264(), send_codec_.H264(),
-                 sizeof(new_send_codec.H264())) != 0) {
+      if (new_send_codec.H264() != *send_codec_.H264()) {
         return true;
       }
       break;
+
     case kVideoCodecGeneric:
       break;
     // Known codecs without payload-specifics
@@ -169,15 +169,9 @@
       return true;
   }
 
-  if (new_send_codec.numberOfSimulcastStreams > 0) {
-    for (unsigned char i = 0; i < new_send_codec.numberOfSimulcastStreams;
-         ++i) {
-      if (memcmp(&new_send_codec.simulcastStream[i],
-                 &send_codec_.simulcastStream[i],
-                 sizeof(new_send_codec.simulcastStream[i])) != 0) {
-        return true;
-      }
-    }
+  for (unsigned char i = 0; i < new_send_codec.numberOfSimulcastStreams; ++i) {
+    if (new_send_codec.simulcastStream[i] != send_codec_.simulcastStream[i])
+      return true;
   }
   return false;
 }