Launch experiment ExcludeTransparentTextsFromBeingLcpEligible

This is to launch ExcludeTransparentTextsFromBeingLcpEligible.
This Cl removes fieldtrial testing config and turns on the
ExcludeTransparentTextsFromBeingLcpEligible flag.

Bug: 375254523
Change-Id: I481579128f53d612b35b091dc0534ded31e9bd6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5959108
Reviewed-by: Ian Clelland <iclelland@chromium.org>
Commit-Queue: Hao Liu <haoliuk@chromium.org>
Reviewed-by: Khushal Sagar <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1374739}

docs/speed/metrics_changelog/2024_10_lcp.md

@@ -0,0 +1,23 @@
+# Largest Contentful Paint Change in Chrome 130
+
+## Exclude transparent text from LCP
+
+When texts are transparent, and with no visible decorations like shadows,
+and strokes, they should be not eligible for LCP. But previously they are. We
+fixed this and did experiment to see if the fix would have impact on the LCP
+metric.
+
+
+Note: this experiment was first landed in Chrome 126:
+[Exclude transparent text with decorations from being skipped for LCP](https://chromium-review.googlesource.com/c/chromium/src/+/5498955),
+and was slowly rolled out.
+
+## How does this affect a site's metrics?
+
+We observed that this feature’s impact on ecosystem metrics was minimal and not
+statistically significant.
+
+## When were users affected?
+
+Launch was the week of Oct 21, 2024, when m130 was in stable, but a limited
+number of early adopters might have seen this change as early as m126.

docs/speed/metrics_changelog/lcp.md

@@ -2,6 +2,8 @@
 
 This is a list of changes to [Largest Contentful Paint](https://web.dev/lcp).
 
+* Chrome 130
+  * Launch feature: [Exclude transparent text from being LCP eligible](2024_10_lcp.md)
 * Chrome 126
   * Launch feature: [Enable NewPresentationFeedbackTimeStamps on Mac to improve the accuracy of the frame display time](2024_06_inp_lcp_fcp.md)
 * Chrome 118

testing/variations/fieldtrial_testing_config.json

@@ -9606,29 +9606,6 @@
             ]
         }
     ],
-    "ExcludeTransparentTextsFromBeingLcpEligible": [
-        {
-            "platforms": [
-                "android",
-                "chromeos",
-                "chromeos_lacros",
-                "fuchsia",
-                "linux",
-                "mac",
-                "windows",
-                "android_webview",
-                "android_weblayer"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "ExcludeTransparentTextsFromBeingLcpEligible"
-                    ]
-                }
-            ]
-        }
-    ],
     "ExpandCompositedCullRect": [
         {
             "platforms": [

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1704,7 +1704,7 @@
     },
     {
       name: "ExcludeTransparentTextsFromBeingLcpEligible",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "ExperimentalContentSecurityPolicyFeatures",