Display Page Lifecycle State in chrome://discards

In the Lifecycle State column, we were showing internal
TabLifecycleUnitStates rather than Page Lifecycle
states. As a result, we were showing "active" for the active, hidden,
and passive page lifecycle states. As chrome://discards will be used by
external developers, we should show Page Lifecycles States from the
spec (https://github.com/WICG/page-lifecycle).

This CL plumbs focus to the discards UI and uses the 3-tuple of
(internal_tab_state, visibility, focus) to compute the page lifecycle
state. Internal states are still shown in parentheses to aid in
TabManager debugging, e.g. "hidden (pending frozen)".

Bug: 856321
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ieb6f0a098cc165c0b7544b3f27a7317f8c78caa1
Reviewed-on: https://chromium-review.googlesource.com/1114282
Commit-Queue: Scott Haseley <shaseley@google.com>
Reviewed-by: Will Harris <wfh@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Shubhie Panicker <panicker@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585560}

chrome/browser/resources/discards/discards.js

@@ -217,11 +217,11 @@ cr.define('discards', function() {
    */
   function visibilityToString(visibility) {
     switch (visibility) {
-      case 0:
+      case mojom.LifecycleUnitVisibility.HIDDEN:
         return 'hidden';
-      case 1:
+      case mojom.LifecycleUnitVisibility.OCCLUDED:
         return 'occluded';
-      case 2:
+      case mojom.LifecycleUnitVisibility.VISIBLE:
         return 'visible';
     }
     assertNotReached('Unknown visibility: ' + visibility);
@@ -235,11 +235,11 @@ cr.define('discards', function() {
    */
   function loadingStateToString(loadingState) {
     switch (loadingState) {
-      case 0:
+      case mojom.LifecycleUnitLoadingState.UNLOADED:
         return 'unloaded';
-      case 1:
+      case mojom.LifecycleUnitLoadingState.LOADING:
         return 'loading';
-      case 2:
+      case mojom.LifecycleUnitLoadingState.LOADED:
         return 'loaded';
     }
     assertNotReached('Unknown loadingState: ' + loadingState);
@@ -248,7 +248,7 @@ cr.define('discards', function() {
   /**
    * Returns a string representation of a discard reason.
    * @param {mojom.LifecycleUnitDiscardReason} reason The discard reason.
-   * @param {string} A string representation of the discarding reason.
+   * @return {string} A string representation of the discarding reason.
    */
   function discardReasonToString(reason) {
     switch (reason) {
@@ -267,25 +267,40 @@ cr.define('discards', function() {
    * @param {mojom.LifecycleUnitState} state The lifecycle state.
    * @param {mojom.LifecycleUnitDiscardReason} reason The discard reason. This
    *     is only used if the state is discard related.
-   * @param {string} A string representation of the lifecycle state, augmented
+   * @param {int} visibility A value in LifecycleUnitVisibility.
+   * @param {boolean} hasFocus Whether or not the tab has input focus.
+   * @return {string} A string representation of the lifecycle state, augmented
    *     with the discard reason if appropriate.
    */
-  function lifecycleStateToString(state, reason) {
+  function lifecycleStateToString(state, reason, visibility, hasFocus) {
+    let pageLifecycleStateFromVisibilityAndFocus = function() {
+      switch (visibility) {
+        case mojom.LifecycleUnitVisibility.HIDDEN:
+        case mojom.LifecycleUnitVisibility.OCCLUDED:
+          // An occluded page is also considered hidden.
+          return 'hidden';
+        case mojom.LifecycleUnitVisibility.VISIBLE:
+          return hasFocus ? 'active' : 'passive';
+      }
+      assertNotReached('Unknown visibility: ' + visibility);
+    };
+
     switch (state) {
       case mojom.LifecycleUnitState.ACTIVE:
-        return 'active';
+        return pageLifecycleStateFromVisibilityAndFocus();
       case mojom.LifecycleUnitState.THROTTLED:
-        return 'throttled';
+        return pageLifecycleStateFromVisibilityAndFocus() + ' (throttled)';
       case mojom.LifecycleUnitState.PENDING_FREEZE:
-        return 'pending frozen';
+        return pageLifecycleStateFromVisibilityAndFocus() + ' (pending frozen)';
       case mojom.LifecycleUnitState.FROZEN:
         return 'frozen';
       case mojom.LifecycleUnitState.PENDING_DISCARD:
-        return 'pending discard (' + discardReasonToString(reason) + ')';
+        return pageLifecycleStateFromVisibilityAndFocus() +
+            ' (pending discard (' + discardReasonToString(reason) + '))';
       case mojom.LifecycleUnitState.DISCARDED:
         return 'discarded (' + discardReasonToString(reason) + ')';
       case mojom.LifecycleUnitState.PENDING_UNFREEZE:
-        return 'pending unfreeze';
+        return 'frozen (pending unfreeze)';
     }
     assertNotReached('Unknown lifecycle state: ' + state);
   }
@@ -401,7 +416,8 @@ cr.define('discards', function() {
     row.querySelector('.state-cell').textContent =
         (info.loadingState != mojom.LifecycleUnitLoadingState.UNLOADED ||
          info.discardCount > 0) ?
-        lifecycleStateToString(info.state, info.discardReason) :
+        lifecycleStateToString(
+            info.state, info.discardReason, info.visibility, info.hasFocus) :
         '';
     row.querySelector('.discard-count-cell').textContent =
         info.discardCount.toString();
@@ -437,7 +453,9 @@ cr.define('discards', function() {
     let discardUrgentEnabled = false;
     if (info.loadingState == mojom.LifecycleUnitLoadingState.UNLOADED) {
       loadEnabled = true;
-    } else if (info.visibility == 0) {
+    } else if (
+        info.visibility == mojom.LifecycleUnitVisibility.HIDDEN ||
+        info.visibility == mojom.LifecycleUnitVisibility.OCCLUDED) {
       // Only tabs that aren't visible can be frozen or discarded for now.
       freezeEnabled = true;
       discardEnabled = true;

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

@@ -58,6 +58,8 @@ struct TabDiscardsInfo {
   double reactivation_score;
   // Site engagement score.
   double site_engagement_score;
+  // Whether or not the tab has input focus.
+  bool has_focus;
 };
 
 // Interface for providing information about discards. Lives in the browser

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

@@ -150,6 +150,11 @@ class DiscardsDetailsProviderImpl : public mojom::DiscardsDetailsProvider {
       if (info->has_reactivation_score)
         info->reactivation_score = reactivation_score.value();
       info->site_engagement_score = GetSiteEngagementScore(contents);
+      // TODO(crbug.com/876340): The focus is used to compute the page lifecycle
+      // state. This should be replaced with the actual page lifecycle state
+      // information from Blink, but this depends on implementing the passive
+      // state and plumbing it to the browser.
+      info->has_focus = lifecycle_unit->GetLastFocusedTime().is_max();
 
       infos.push_back(std::move(info));
     }