RC: Validate state transitions in TabLifecycleUnit.

This CL adds a function that determines if a state transition is valid
in TabLifecycleUnit. This will help us ensure that things work properly
as we add more possible state transitions (e.g. periodic unfreeze).

Bug: 775644
Change-Id: I89e90021415f68edbed1aca1d6f0052057cd44e9
Reviewed-on: https://chromium-review.googlesource.com/1097550Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567995}

chrome/browser/resource_coordinator/discard_metrics_lifecycle_unit_observer_unittest.cc

@@ -58,19 +58,23 @@ TEST_F(DiscardMetricsLifecycleUnitObserverTest, DiscardReloadCount) {
   histograms_.ExpectTotalCount(kDiscardCountHistogram, 0);
   histograms_.ExpectTotalCount(kReloadCountHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kDiscardCountHistogram, 1);
   histograms_.ExpectTotalCount(kReloadCountHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE);
+  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kDiscardCountHistogram, 1);
   histograms_.ExpectTotalCount(kReloadCountHistogram, 1);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kDiscardCountHistogram, 2);
   histograms_.ExpectTotalCount(kReloadCountHistogram, 1);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE);
+  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kDiscardCountHistogram, 2);
   histograms_.ExpectTotalCount(kReloadCountHistogram, 2);
 }
@@ -78,11 +82,13 @@ TEST_F(DiscardMetricsLifecycleUnitObserverTest, DiscardReloadCount) {
 TEST_F(DiscardMetricsLifecycleUnitObserverTest, DiscardToReloadTime) {
   histograms_.ExpectTotalCount(kDiscardToReloadTimeHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   test_clock_.Advance(kShortDelay);
   histograms_.ExpectTotalCount(kDiscardToReloadTimeHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE);
+  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTimeBucketCount(kDiscardToReloadTimeHistogram, kShortDelay,
                                     1);
 }
@@ -93,11 +99,13 @@ TEST_F(DiscardMetricsLifecycleUnitObserverTest, InactiveToReloadTime) {
   const base::TimeTicks last_focused_time = NowTicks();
   lifecycle_unit_->SetLastFocusedTime(last_focused_time);
   test_clock_.Advance(kShortDelay);
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   test_clock_.Advance(kShortDelay);
   histograms_.ExpectTotalCount(kInactiveToReloadTimeHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE);
+  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTimeBucketCount(kInactiveToReloadTimeHistogram,
                                     2 * kShortDelay, 1);
 }
@@ -113,7 +121,8 @@ TEST_F(DiscardMetricsLifecycleUnitObserverTest,
        ReloadToCloseTimeDiscardedButNotReloaded) {
   histograms_.ExpectTotalCount(kReloadToCloseTimeHistogram, 0);
 
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kReloadToCloseTimeHistogram, 0);
 
   lifecycle_unit_.reset();
@@ -124,11 +133,13 @@ TEST_F(DiscardMetricsLifecycleUnitObserverTest, ReloadToCloseTime) {
   histograms_.ExpectTotalCount(kReloadToCloseTimeHistogram, 0);
 
   test_clock_.Advance(kShortDelay * 1);
-  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit_->SetState(LifecycleUnitState::DISCARDED,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kReloadToCloseTimeHistogram, 0);
 
   test_clock_.Advance(kShortDelay * 2);
-  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE);
+  lifecycle_unit_->SetState(LifecycleUnitState::ACTIVE,
+                            LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   histograms_.ExpectTotalCount(kReloadToCloseTimeHistogram, 0);
 
   test_clock_.Advance(kShortDelay * 4);

chrome/browser/resource_coordinator/lifecycle_unit_base.cc

@@ -40,18 +40,20 @@ ukm::SourceId LifecycleUnitBase::GetUkmSourceId() const {
   return ukm::kInvalidSourceId;
 }
 
-void LifecycleUnitBase::SetState(LifecycleUnitState state) {
+void LifecycleUnitBase::SetState(LifecycleUnitState state,
+                                 LifecycleUnitStateChangeReason reason) {
   if (state == state_)
     return;
   LifecycleUnitState last_state = state_;
   state_ = state;
-  OnLifecycleUnitStateChanged(last_state);
+  OnLifecycleUnitStateChanged(last_state, reason);
   for (auto& observer : observers_)
     observer.OnLifecycleUnitStateChanged(this, last_state);
 }
 
 void LifecycleUnitBase::OnLifecycleUnitStateChanged(
-    LifecycleUnitState last_state) {}
+    LifecycleUnitState last_state,
+    LifecycleUnitStateChangeReason reason) {}
 
 void LifecycleUnitBase::OnLifecycleUnitVisibilityChanged(
     content::Visibility visibility) {

chrome/browser/resource_coordinator/lifecycle_unit_base.h

@@ -13,6 +13,7 @@
 namespace resource_coordinator {
 
 using ::mojom::LifecycleUnitState;
+using ::mojom::LifecycleUnitStateChangeReason;
 
 // Base class for a LifecycleUnit.
 class LifecycleUnitBase : public LifecycleUnit {
@@ -30,12 +31,17 @@ class LifecycleUnitBase : public LifecycleUnit {
 
  protected:
   // Sets the state of this LifecycleUnit to |state| and notifies observers.
-  void SetState(LifecycleUnitState state);
+  // |reason| indicates what caused the state change.
+  void SetState(LifecycleUnitState state,
+                LifecycleUnitStateChangeReason reason);
 
   // Invoked when the state of the LifecycleUnit changes, before external
   // observers are notified. Derived classes can override to add their own
-  // logic. The default implementation is empty.
-  virtual void OnLifecycleUnitStateChanged(LifecycleUnitState last_state);
+  // logic. The default implementation is empty. |last_state| is the state
+  // before the change and |reason| indicates what caused the change.
+  virtual void OnLifecycleUnitStateChanged(
+      LifecycleUnitState last_state,
+      LifecycleUnitStateChangeReason reason);
 
   // Notifies observers that the visibility of the LifecycleUnit has changed.
   void OnLifecycleUnitVisibilityChanged(content::Visibility visibility);

chrome/browser/resource_coordinator/lifecycle_unit_base_unittest.cc

@@ -59,11 +59,13 @@ TEST(LifecycleUnitBaseTest, SetStateNotifiesObservers) {
   // Observer is notified when the state changes.
   EXPECT_CALL(observer, OnLifecycleUnitStateChanged(&lifecycle_unit,
                                                     lifecycle_unit.GetState()));
-  lifecycle_unit.SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit.SetState(LifecycleUnitState::DISCARDED,
+                          LifecycleUnitStateChangeReason::BROWSER_INITIATED);
   testing::Mock::VerifyAndClear(&observer);
 
   // Observer isn't notified when the state stays the same.
-  lifecycle_unit.SetState(LifecycleUnitState::DISCARDED);
+  lifecycle_unit.SetState(LifecycleUnitState::DISCARDED,
+                          LifecycleUnitStateChangeReason::BROWSER_INITIATED);
 
   lifecycle_unit.RemoveObserver(&observer);
 }

chrome/browser/resource_coordinator/tab_lifecycle_unit.h

@@ -143,8 +143,13 @@ class TabLifecycleUnitSource::TabLifecycleUnit
   // Returns the RenderProcessHost associated with this tab.
   content::RenderProcessHost* GetRenderProcessHost() const;
 
+  // Initializes |freeze_timeout_timer_| if not already initialized.
+  void EnsureFreezeTimeoutTimerInitialized();
+
   // LifecycleUnitBase:
-  void OnLifecycleUnitStateChanged(LifecycleUnitState last_state) override;
+  void OnLifecycleUnitStateChanged(
+      LifecycleUnitState last_state,
+      LifecycleUnitStateChangeReason reason) override;
 
   // content::WebContentsObserver:
   void DidStartLoading() override;

chrome/browser/resource_coordinator/tab_manager.h

@@ -206,7 +206,7 @@ class TabManager : public LifecycleUnitObserver,
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, PauseAndResumeBackgroundTabOpening);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest,
                            ProactiveFastShutdownSharedTabProcess);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest,
+  FRIEND_TEST_ALL_PREFIXES(TabManagerTestWithTwoTabs,
                            ProactiveFastShutdownSingleTabProcess);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest,
                            ProactiveFastShutdownWithBeforeunloadHandler);
@@ -229,7 +229,8 @@ class TabManager : public LifecycleUnitObserver,
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest,
                            TrackingNumberOfLoadedLifecycleUnits);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, UrgentFastShutdownSharedTabProcess);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, UrgentFastShutdownSingleTabProcess);
+  FRIEND_TEST_ALL_PREFIXES(TabManagerTestWithTwoTabs,
+                           UrgentFastShutdownSingleTabProcess);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest,
                            UrgentFastShutdownWithBeforeunloadHandler);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, UrgentFastShutdownWithUnloadHandler);