MediaCapabilities: Update fieldtrial_testing_config

Patch removes stale config for past DB window experiment and adds a new
config for MediaLearningSmoothnessExperiment.

Bug: 1049339
Change-Id: I5be2b21c0a5be90734a82e389f4d161941e582ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2253460
Commit-Queue: Chrome Cunningham <chcunningham@chromium.org>
Auto-Submit: Chrome Cunningham <chcunningham@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781635}

testing/variations/fieldtrial_testing_config.json

@@ -3932,23 +3932,22 @@
             ]
         }
     ],
-    "MediaCapabilitiesWithParameters": [
+    "MediaFoundationAsyncH264Encoding": [
         {
             "platforms": [
-                "android",
-                "chromeos",
-                "linux",
-                "mac",
                 "windows"
             ],
             "experiments": [
                 {
-                    "name": "DBWindow5000Frames_20190225"
+                    "name": "Enabled",
+                    "enable_features": [
+                        "MediaFoundationAsyncH264Encoding"
+                    ]
                 }
             ]
         }
     ],
-    "MediaFoundationAsyncH264Encoding": [
+    "MediaFoundationVP8Decoding": [
         {
             "platforms": [
                 "windows"
@@ -3957,28 +3956,32 @@
                 {
                     "name": "Enabled",
                     "enable_features": [
-                        "MediaFoundationAsyncH264Encoding"
+                        "MediaFoundationVP8Decoding"
                     ]
                 }
             ]
         }
     ],
-    "MediaFoundationVP8Decoding": [
+    "MediaHistory": [
         {
             "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac",
                 "windows"
             ],
             "experiments": [
                 {
                     "name": "Enabled",
                     "enable_features": [
-                        "MediaFoundationVP8Decoding"
+                        "UseMediaHistoryStore"
                     ]
                 }
             ]
         }
     ],
-    "MediaHistory": [
+    "MediaLearningSmoothnessExperiment": [
         {
             "platforms": [
                 "android",
@@ -3991,7 +3994,8 @@
                 {
                     "name": "Enabled",
                     "enable_features": [
-                        "UseMediaHistoryStore"
+                        "MediaLearningFramework",
+                        "MediaLearningSmoothnessExperiment"
                     ]
                 }
             ]