[Omnibox] Enable reducing Omnibox Clipboard suggestion age by default

Enable reducing Omnibox Clipboard suggestion age from 1 hour to 10
minutes by default.

This CL is a kind of prerequisite for cr/307908522

Bug: 948235
Change-Id: I15540a847bbe645843024dc3a691673c6372a89a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2181042Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Ender <ender@google.com>
Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Gang Wu <gangwu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#766459}

components/open_from_clipboard/clipboard_recent_content.cc

@@ -38,7 +38,8 @@ base::TimeDelta ClipboardRecentContent::MaximumAgeOfClipboard() {
   // Identify the current setting for this parameter from the feature, using
   // 3600 seconds (1 hour) as a default if the parameter is not set.
   // On iOS, the default is 600 seconds (10 minutes).
-#if defined(OS_IOS)
+  // TODO(gangwu) : Remove this feature flag after full launched in Android.
+#if defined(OS_IOS) || defined(OS_ANDROID)
   int default_maximum_age = 600;
 #else
   int default_maximum_age = 3600;

testing/variations/fieldtrial_testing_config.json

@@ -1437,6 +1437,24 @@
             ]
         }
     ],
+    "ClipboardMaximumAge": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled_V2",
+                    "params": {
+                        "UIClipboardMaximumAge": "600"
+                    },
+                    "enable_features": [
+                        "ClipboardMaximumAge"
+                    ]
+                }
+            ]
+        }
+    ],
     "CompositeCrossOriginIframes": [
         {
             "platforms": [
@@ -3774,14 +3792,12 @@
                 {
                     "name": "AndroidExperiments",
                     "params": {
-                        "UIClipboardMaximumAge": "600",
                         "ZeroSuggestVariant:1:*": "Local",
                         "ZeroSuggestVariant:7:*": "Local",
                         "ZeroSuggestVariant:8:*": "Local",
                         "rounded_edges": "true"
                     },
                     "enable_features": [
-                        "ClipboardMaximumAge",
                         "OmniboxDisableInstantExtendedLimit",
                         "OmniboxHistoryQuickProviderAllowButDoNotScoreMidwordTerms",
                         "OmniboxHistoryQuickProviderAllowMidwordContinuations",