[Lifecycle] Update testing config for proactive freeze and discard experiment.

This updates field_trial_testing_config.json with the parameters that we
plan to use to experiment with proactive freeze and discard on beta.

PageAlmostIdle feature is independant from ProactiveTabFreezeAndDiscard.

SiteCharacteristicsDatabase feature is required to enable
ProactiveTabFreezeAndDiscard, so they need to be enabled by the same
study.

stop-non-timers-in-background defines the effect of freezing a tab,
so it needs to be in the same study as ProactiveTabFreezeAndDiscard.

Bug: 775644
Change-Id: I8ef64a716585a6284e9744c93cf5dfc58a22f77f
Reviewed-on: https://chromium-review.googlesource.com/1188862
Commit-Queue: François Doray <fdoray@chromium.org>
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586299}

testing/variations/fieldtrial_testing_config.json

@@ -3018,7 +3018,7 @@
             ]
         }
     ],
-    "PageAlmostIdleAndLocalDB": [
+    "PageAlmostIdle": [
         {
             "platforms": [
                 "chromeos",
@@ -3033,8 +3033,7 @@
                         "mainThreadTaskLoadLowThreshold": "25"
                     },
                     "enable_features": [
-                        "PageAlmostIdle",
-                        "SiteCharacteristicsDatabase"
+                        "PageAlmostIdle"
                     ]
                 }
             ]
@@ -3437,14 +3436,18 @@
             ],
             "experiments": [
                 {
-                    "name": "FreezeAndDiscardWithUnfreeze",
+                    "name": "FreezeAndDiscard",
                     "params": {
+                        "HighLoadedTabCount": "10000",
                         "ShouldPeriodicallyUnfreeze": "true",
-                        "ShouldProactivelyDiscard": "true"
+                        "ShouldProactivelyDiscard": "true",
+                        "ShouldProtectTabsSharingBrowsingInstance": "true"
                     },
                     "enable_features": [
                         "PageLifecycle",
-                        "ProactiveTabFreezeAndDiscard"
+                        "ProactiveTabFreezeAndDiscard",
+                        "SiteCharacteristicsDatabase",
+                        "stop-non-timers-in-background"
                     ]
                 }
             ]