In chrome://discards, add 'Can Freeze?'/'Can Discard?' columns

The 'Can Discard?' column indicates proactive discards, not urgent discards.

Each cell in those columns shows a checkmark or crossmark, with a
'[View Reason]' link. Hovering the link shows a tooltip with the reasons why
it can't be frozen/discarded.

The 'View Reason' button is disabled if the tab _can_ be frozen/discarded, since
there are no failure reasons to show.

Also, remove the 'Media' column, since it's redundant now.

Screenshot (apologies for external contributors):
https://screenshot.googleplex.com/n9oDCgM3ffj

Bug: 864149
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ied07835a5eae7a80989226a3662dc12d3e9ee9b2
Reviewed-on: https://chromium-review.googlesource.com/1140368
Commit-Queue: Sébastien Marchand <sebmarchand@chromium.org>
Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576216}

chrome/browser/resource_coordinator/tab_lifecycle_unit.cc

@@ -167,21 +167,37 @@ StateChangeReason DiscardReasonToStateChangeReason(DiscardReason reason) {
   }
 }
 
-void CheckFeatureUsage(SiteFeatureUsage feature_usage,
-                       DecisionDetails* details,
-                       DecisionFailureReason heuristic_failure_reason) {
-  DCHECK(details);
+struct FeatureUsageEntry {
+  SiteFeatureUsage usage;
+  DecisionFailureReason failure_reason;
+};
 
-  switch (feature_usage) {
-    case SiteFeatureUsage::kSiteFeatureInUse:
-      details->AddReason(heuristic_failure_reason);
-      return;
-    case SiteFeatureUsage::kSiteFeatureUsageUnknown:
+void CheckFeatureUsage(const SiteCharacteristicsDataReader* reader,
+                       DecisionDetails* details) {
+  const FeatureUsageEntry features[] = {
+      {reader->UsesAudioInBackground(), DecisionFailureReason::HEURISTIC_AUDIO},
+      {reader->UpdatesFaviconInBackground(),
+       DecisionFailureReason::HEURISTIC_FAVICON},
+      {reader->UsesNotificationsInBackground(),
+       DecisionFailureReason::HEURISTIC_NOTIFICATIONS},
+      {reader->UpdatesTitleInBackground(),
+       DecisionFailureReason::HEURISTIC_TITLE}};
+
+  // Avoid adding 'insufficient observation' reason multiple times.
+  bool insufficient_observation = false;
+
+  const auto* last = features + base::size(features);
+  for (const auto* f = features; f != last; f++) {
+    if (f->usage == SiteFeatureUsage::kSiteFeatureInUse) {
+      details->AddReason(f->failure_reason);
+    } else if (f->usage == SiteFeatureUsage::kSiteFeatureUsageUnknown) {
+      insufficient_observation = true;
+    }
+  }
+
+  if (insufficient_observation) {
     details->AddReason(
         DecisionFailureReason::HEURISTIC_INSUFFICIENT_OBSERVATION);
-      return;
-    case SiteFeatureUsage::kSiteFeatureNotInUse:
-      return;
   }
 }
 
@@ -209,17 +225,7 @@ void CheckIfTabCanCommunicateWithUserWhileInBackground(
 
   // TODO(sebmarchand): Add a failure reason for when the data isn't ready yet.
 
-  CheckFeatureUsage(reader->UsesAudioInBackground(), details,
-                    DecisionFailureReason::HEURISTIC_AUDIO);
-
-  CheckFeatureUsage(reader->UpdatesFaviconInBackground(), details,
-                    DecisionFailureReason::HEURISTIC_FAVICON);
-
-  CheckFeatureUsage(reader->UsesNotificationsInBackground(), details,
-                    DecisionFailureReason::HEURISTIC_NOTIFICATIONS);
-
-  CheckFeatureUsage(reader->UpdatesTitleInBackground(), details,
-                    DecisionFailureReason::HEURISTIC_TITLE);
+  CheckFeatureUsage(reader.get(), details);
 }
 
 InterventionPolicyDatabase* GetInterventionPolicyDatabase() {

chrome/browser/resource_coordinator/tab_lifecycle_unit_unittest.cc

@@ -183,6 +183,10 @@ void TabLifecycleUnitTest::TestCannotDiscardBasedOnHeuristicUsage(
                                                &decision_details));
     EXPECT_FALSE(decision_details.IsPositive());
     EXPECT_EQ(failure_reason, decision_details.FailureReason());
+    // There should only be one reason (e.g. no duplicates).
+    EXPECT_THAT(
+        decision_details.reasons(),
+        ::testing::ElementsAre(DecisionDetails::Reason(failure_reason)));
   }
 
   // Heuristics shouldn't be considered for urgent or external tab discarding.

chrome/browser/resources/discards/discards.css

@@ -92,7 +92,7 @@ table td.utility-rank-cell {
   text-align: center;
 }
 
-table td div.is-auto-discardable-link,
+table td div[is=action-link],
 table td.actions-cell {
   font-size: 0.6rem;
 }
@@ -115,3 +115,26 @@ th[data-sort-reverse].sort-column div.header-cell-container::after {
   content: '▼';
   opacity: 1;
 }
+
+.tooltip-container {
+  position: relative;
+}
+
+.tooltip {
+  background: black;
+  color: white;
+  display: none;
+  font-size: 0.75rem;
+  left: 50%;
+  margin-left: -100px;
+  margin-top: 4px;
+  padding: 4px;
+  position: absolute;
+  top: 100%;
+  width: 200px;
+  z-index: 1;
+}
+
+.tooltip-container:hover > .tooltip {
+  display: block;
+}

chrome/browser/resources/discards/discards.html

@@ -85,9 +85,18 @@ general use and is not localized.
               </div>
             </div>
           </th>
-          <th data-sort-key="isMedia">
+          <th data-sort-key="canFreeze">
             <div class="header-cell-container">
-              Media
+              <div>
+                <div>Can freeze?</div>
+              </div>
+            </div>
+          </th>
+          <th data-sort-key="canDiscard">
+            <div class="header-cell-container">
+              <div>
+                <div>Can discard?</div>
+              </div>
             </div>
           </th>
           <th data-sort-key="discardCount">
@@ -136,7 +145,20 @@ general use and is not localized.
         <td class="visibility-cell"></td>
         <td class="loading-state-cell"></td>
         <td class="state-cell"></td>
-        <td class="is-media-cell boolean-cell"></td>
+        <td class="can-freeze-cell boolean-cell">
+          <div class="can-freeze-div"></div>
+          <div is="action-link" class="tooltip-container can-freeze-link">
+            [View Reason]
+            <div class="tooltip can-freeze-tooltip"></div>
+          </div>
+        </td>
+        <td class="can-discard-cell boolean-cell">
+          <div class="can-discard-div"></div>
+          <div is="action-link" class="tooltip-container can-discard-link">
+            [View Reason]
+            <div class="tooltip can-discard-tooltip"></div>
+          </div>
+        </td>
         <td class="discard-count-cell"></td>
         <td class="is-auto-discardable-cell boolean-cell">
           <div class="is-auto-discardable-div"></div>

chrome/browser/resources/discards/discards.js

@@ -64,7 +64,7 @@ cr.define('discards', function() {
     }
 
     // Compares boolean fields.
-    if (['isMedia', 'isAutoDiscardable'].includes(sortKey)) {
+    if (['canFreeze', 'canDiscard', 'isAutoDiscardable'].includes(sortKey)) {
       if (val1 == val2)
         return 0;
       return val1 ? 1 : -1;
@@ -185,7 +185,7 @@ cr.define('discards', function() {
    * @return {string} A string representing the bool.
    */
   function boolToString(bool) {
-    return bool ? '✔' : '\xa0';
+    return bool ? '✔' : '✘️';
   }
 
   /**
@@ -276,7 +276,6 @@ cr.define('discards', function() {
           .then(stableUpdateTabDiscardsInfoTable());
     });
 
-    // Set up the listeners for load links.
     let loadListener = function(e) {
       // Get the info backing this row.
       let info = infos[getRowIndex(e.target)];
@@ -348,8 +347,10 @@ cr.define('discards', function() {
         visibilityToString(info.visibility);
     row.querySelector('.loading-state-cell').textContent =
         loadingStateToString(info.loadingState);
-    row.querySelector('.is-media-cell').textContent =
-        boolToString(info.isMedia);
+    row.querySelector('.can-freeze-div').textContent =
+        boolToString(info.canFreeze);
+    row.querySelector('.can-discard-div').textContent =
+        boolToString(info.canDiscard);
     // The lifecycle state is meaningless for 'unloaded' tabs.
     row.querySelector('.state-cell').textContent =
         (info.loadingState != mojom.LifecycleUnitLoadingState.UNLOADED) ?
@@ -362,7 +363,17 @@ cr.define('discards', function() {
     row.querySelector('.last-active-cell').textContent =
         lastActiveToString(info.lastActiveSeconds);
 
+    // Update the tooltips with 'Can Freeze/Discard?' reasons.
+    row.querySelector('.can-freeze-tooltip').innerHTML =
+        info.cannotFreezeReasons.join('<br />');
+    row.querySelector('.can-discard-tooltip').innerHTML =
+        info.cannotDiscardReasons.join('<br />');
+
     row.querySelector('.is-auto-discardable-link').removeAttribute('disabled');
+    setActionLinkEnabled(
+        row.querySelector('.can-freeze-link'), !info.canFreeze);
+    setActionLinkEnabled(
+        row.querySelector('.can-discard-link'), !info.canDiscard);
     let loadLink = row.querySelector('.load-link');
     let freezeLink = row.querySelector('.freeze-link');
     let discardLink = row.querySelector('.discard-link');

chrome/browser/ui/webui/discards/discards.mojom

@@ -26,9 +26,14 @@ struct TabDiscardsInfo {
   LifecycleUnitLoadingState loading_state;
   // The state of the LifecycleUnit.
   LifecycleUnitState state;
-  // If the tab is currently using media functionality (casting, WebRTC, playing
-  // audio, etc) this is true.
-  bool is_media;
+  // Whether the tab can be frozen.
+  bool can_freeze;
+  // List of human-readable reasons why a tab can't be frozen.
+  array<string> cannot_freeze_reasons;
+  // Whether the tab can be discarded.
+  bool can_discard;
+  // List of human-readable reasons why a tab can't be discarded.
+  array<string> cannot_discard_reasons;
   // The number of times this tab has been discarded in the current browser
   // session.
   int32 discard_count;

chrome/browser/ui/webui/discards/discards_ui.cc

@@ -122,7 +122,13 @@ class DiscardsDetailsProviderImpl : public mojom::DiscardsDetailsProvider {
           GetLifecycleUnitVisibility(lifecycle_unit->GetVisibility());
       info->loading_state = lifecycle_unit->GetLoadingState();
       info->state = lifecycle_unit->GetState();
-      info->is_media = tab_lifecycle_unit_external->IsMediaTab();
+      resource_coordinator::DecisionDetails freeze_details;
+      info->can_freeze = lifecycle_unit->CanFreeze(&freeze_details);
+      info->cannot_freeze_reasons = freeze_details.GetFailureReasonStrings();
+      resource_coordinator::DecisionDetails discard_details;
+      info->can_discard = lifecycle_unit->CanDiscard(
+          resource_coordinator::DiscardReason::kProactive, &discard_details);
+      info->cannot_discard_reasons = discard_details.GetFailureReasonStrings();
       info->discard_count = tab_lifecycle_unit_external->GetDiscardCount();
       info->utility_rank = rank++;
       const base::TimeTicks last_focused_time =

chrome/test/data/webui/discards/discards_browsertest.js

@@ -22,7 +22,8 @@ TEST_F('DiscardsTest', 'CompareTabDiscardsInfo', function() {
     tabUrl: 'http://urlone.com',
     visibility: 0,  // hidden
     state: 0,       // active
-    isMedia: false,
+    canFreeze: false,
+    canDiscard: false,
     isAutoDiscardable: false,
     discardCount: 0,
     utilityRank: 0,
@@ -33,7 +34,8 @@ TEST_F('DiscardsTest', 'CompareTabDiscardsInfo', function() {
     tabUrl: 'http://urltwo.com',
     visibility: 1,  // occluded
     state: 3,       // frozen
-    isMedia: true,
+    canFreeze: true,
+    canDiscard: true,
     isFrozen: true,
     isDiscarded: true,
     isAutoDiscardable: true,
@@ -42,8 +44,8 @@ TEST_F('DiscardsTest', 'CompareTabDiscardsInfo', function() {
     lastActiveSeconds: 1
   };
 
-  ['title', 'tabUrl', 'visibility', 'state', 'isMedia', 'isAutoDiscardable',
-   'discardCount', 'utilityRank', 'lastActiveSeconds']
+  ['title', 'tabUrl', 'visibility', 'state', 'canFreeze', 'canDiscard',
+   'isAutoDiscardable', 'discardCount', 'utilityRank', 'lastActiveSeconds']
       .forEach((sortKey) => {
         assertTrue(
             discards.compareTabDiscardsInfos(sortKey, dummy1, dummy2) < 0);