ThumbnailTabHelper: Capture thumbnail when page load finishes

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 0fd1b2383050750f22955e9869957166f861f770..eda0b26aa6324dc708f1ac0b7a4e5c611363d391 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2792,6 +2792,11 @@ const FeatureEntry kFeatureEntries[] = {
      SINGLE_VALUE_TYPE(switches::kShowCertLink)},
 #endif
 
+    {"capture-thumbnail-on-load-finished",
+     flag_descriptions::kCaptureThumbnailOnLoadFinishedName,
+     flag_descriptions::kCaptureThumbnailOnLoadFinishedDescription, kOsDesktop,
+     FEATURE_VALUE_TYPE(features::kCaptureThumbnailOnLoadFinished)},
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.