ContentCapture: Enable UserActivateDelay by default

Bug: 1114819
Change-Id: Iba1461d2269d5d07631066c1afb7564da8f12bf3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2536015Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Michael Bai <michaelbai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827297}

third_party/blink/common/features.cc

@@ -750,7 +750,7 @@ const base::Feature kContentCaptureConstantStreaming = {
 
 // Enables the user activated exponential delay in the ContentCapture task.
 const base::Feature kContentCaptureUserActivatedDelay = {
-    "ContentCaptureUserActivatedDelay", base::FEATURE_DISABLED_BY_DEFAULT};
+    "ContentCaptureUserActivatedDelay", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Dispatches a fake fetch event to a service worker to check the offline
 // capability of the site before promoting installation.