media/gpu/vaapi/VP9Encoder: Fix the assignment of ts_rate_decimator

Bug: 1030199
Test: vp9_encoder_unittest
Change-Id: Id6cc6779c6632d778e8ef664c66a440252358520
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359973
Auto-Submit: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799101}

media/gpu/vaapi/vp9_encoder.cc

@@ -147,7 +147,7 @@ libvpx::VP9RateControlRtcConfig CreateRateControlConfig(
     rc_cfg.min_quantizers[ti] = rc_cfg.min_quantizer;
     rc_cfg.layer_target_bitrate[ti] = base::checked_cast<int>(
         bitrate_allocation.GetBitrateBps(0, ti) / 1000.0);
-    rc_cfg.ts_rate_decimator[ti] = 1u << ti;
+    rc_cfg.ts_rate_decimator[ti] = 1u << (num_temporal_layers - ti - 1);
   }
   return rc_cfg;
 }

media/gpu/vaapi/vp9_encoder_unittest.cc

@@ -152,7 +152,7 @@ MATCHER_P4(MatchRtcConfigWithRates,
         static_cast<int>(bitrate_allocation.GetBitrateBps(0, i) / 1000.0)) {
       return false;
     }
-    if (arg.ts_rate_decimator[i] != (1 << i))
+    if (arg.ts_rate_decimator[i] != (1 << (num_temporal_layers - i - 1)))
       return false;
   }