Viz: Add Fieldtrial test config for GL SolidColorQuad fast draw feature

Adds fieldtrial testing config for Viz GLSolidColorQuad fast draw
experiment.

Bug: 1134771
Change-Id: Ia30ba3b1c23a2b980993556d8f90c9f98a57d72d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2450912Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Malay Keshav <malaykeshav@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813961}

testing/variations/fieldtrial_testing_config.json

@@ -7241,6 +7241,26 @@
             ]
         }
     ],
+    "VizGLFastSolidColorDraw": [
+        {
+            "platforms": [
+                "android",
+                "android_webview",
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "VizGLFastSolidColorDraw",
+                    "enable_features": [
+                        "FastSolidColorDraw"
+                    ]
+                }
+            ]
+        }
+    ],
     "Vulkan": [
         {
             "platforms": [