RC: Add LifecycleUnit::Unfreeze().

This will be used to periodically unfreeze LifecycleUnits, to allow
them to update their state.

Bug: 775644
Change-Id: I498930c8a555ddf3581099e61972aaeac6a36d91
Reviewed-on: https://chromium-review.googlesource.com/1099973
Commit-Queue: François Doray <fdoray@chromium.org>
Reviewed-by: Fadi Meawad <fmeawad@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568451}

chrome/browser/resource_coordinator/lifecycle_unit.h

@@ -120,10 +120,6 @@ class LifecycleUnit {
   // successful.
   virtual bool Load() = 0;
 
-  // Request that the LifecycleUnit be frozen, return true if the request is
-  // successfully sent.
-  virtual bool Freeze() = 0;
-
   // Returns the estimated number of kilobytes that would be freed if this
   // LifecycleUnit was discarded.
   //
@@ -154,6 +150,13 @@ class LifecycleUnit {
   virtual bool CanDiscard(DiscardReason reason,
                           DecisionDetails* decision_details) const = 0;
 
+  // Request that the LifecycleUnit be frozen, return true if the request is
+  // successfully sent.
+  virtual bool Freeze() = 0;
+
+  // Unfreezes this LifecycleUnit. Returns true on success.
+  virtual bool Unfreeze() = 0;
+
   // Discards this LifecycleUnit.
   //
   // TODO(fdoray): Consider handling urgent discard with groups of

chrome/browser/resource_coordinator/tab_lifecycle_unit.cc

@@ -67,6 +67,9 @@ bool IsValidStateChange(LifecycleUnitState from,
     }
     case LifecycleUnitState::PENDING_FREEZE: {
       switch (to) {
+        // Unfreeze() is called.
+        case LifecycleUnitState::ACTIVE:
+          return reason == StateChangeReason::BROWSER_INITIATED;
         // Discard(kProactive) is called.
         case LifecycleUnitState::PENDING_DISCARD:
           return reason == StateChangeReason::BROWSER_INITIATED;
@@ -83,9 +86,12 @@ bool IsValidStateChange(LifecycleUnitState from,
     }
     case LifecycleUnitState::FROZEN: {
       switch (to) {
-        // The renderer re-activates the page because it became visible.
-        case LifecycleUnitState::ACTIVE:
-          return reason == StateChangeReason::RENDERER_INITIATED;
+        // Unfreeze() is called or the renderer re-activates the page because it
+        // became visible.
+        case LifecycleUnitState::ACTIVE: {
+          return reason == StateChangeReason::BROWSER_INITIATED ||
+                 reason == StateChangeReason::RENDERER_INITIATED;
+        }
         // Discard(kProactive|kUrgent|kExternal) is called.
         case LifecycleUnitState::DISCARDED: {
           return reason == StateChangeReason::BROWSER_INITIATED ||
@@ -328,19 +334,6 @@ bool TabLifecycleUnitSource::TabLifecycleUnit::Load() {
   return true;
 }
 
-bool TabLifecycleUnitSource::TabLifecycleUnit::Freeze() {
-  if (!IsValidStateChange(GetState(), LifecycleUnitState::PENDING_FREEZE,
-                          StateChangeReason::BROWSER_INITIATED)) {
-    return false;
-  }
-
-  SetState(LifecycleUnitState::PENDING_FREEZE,
-           StateChangeReason::BROWSER_INITIATED);
-  GetWebContents()->SetPageFrozen(true);
-
-  return true;
-}
-
 int TabLifecycleUnitSource::TabLifecycleUnit::
     GetEstimatedMemoryFreedOnDiscardKB() const {
 #if defined(OS_CHROMEOS)
@@ -502,6 +495,37 @@ bool TabLifecycleUnitSource::TabLifecycleUnit::CanDiscard(
   return decision_details->IsPositive();
 }
 
+bool TabLifecycleUnitSource::TabLifecycleUnit::Freeze() {
+  if (!IsValidStateChange(GetState(), LifecycleUnitState::PENDING_FREEZE,
+                          StateChangeReason::BROWSER_INITIATED)) {
+    return false;
+  }
+
+  // WebContents::SetPageFrozen() DCHECKs if the page is visible.
+  if (GetWebContents()->GetVisibility() == content::Visibility::VISIBLE)
+    return false;
+
+  SetState(LifecycleUnitState::PENDING_FREEZE,
+           StateChangeReason::BROWSER_INITIATED);
+  GetWebContents()->SetPageFrozen(true);
+  return true;
+}
+
+bool TabLifecycleUnitSource::TabLifecycleUnit::Unfreeze() {
+  if (!IsValidStateChange(GetState(), LifecycleUnitState::ACTIVE,
+                          StateChangeReason::BROWSER_INITIATED)) {
+    return false;
+  }
+
+  // WebContents::SetPageFrozen() DCHECKs if the page is visible.
+  if (GetWebContents()->GetVisibility() == content::Visibility::VISIBLE)
+    return false;
+
+  SetState(LifecycleUnitState::ACTIVE, StateChangeReason::BROWSER_INITIATED);
+  GetWebContents()->SetPageFrozen(false);
+  return true;
+}
+
 bool TabLifecycleUnitSource::TabLifecycleUnit::Discard(DiscardReason reason) {
   // Can't discard a tab when it isn't in a tabstrip.
   if (!tab_strip_model_)

chrome/browser/resource_coordinator/tab_lifecycle_unit.h

@@ -91,12 +91,13 @@ class TabLifecycleUnitSource::TabLifecycleUnit
   content::Visibility GetVisibility() const override;
   LifecycleUnitLoadingState GetLoadingState() const override;
   bool Load() override;
-  bool Freeze() override;
   int GetEstimatedMemoryFreedOnDiscardKB() const override;
   bool CanPurge() const override;
   bool CanFreeze(DecisionDetails* decision_details) const override;
   bool CanDiscard(DiscardReason reason,
                   DecisionDetails* decision_details) const override;
+  bool Freeze() override;
+  bool Unfreeze() override;
   bool Discard(DiscardReason discard_reason) override;
   ukm::SourceId GetUkmSourceId() const override;
 

chrome/browser/resource_coordinator/test_lifecycle_unit.cc

@@ -52,10 +52,6 @@ bool TestLifecycleUnit::Load() {
   return false;
 }
 
-bool TestLifecycleUnit::Freeze() {
-  return false;
-}
-
 int TestLifecycleUnit::GetEstimatedMemoryFreedOnDiscardKB() const {
   return 0;
 }
@@ -73,6 +69,14 @@ bool TestLifecycleUnit::CanDiscard(DiscardReason reason,
   return can_discard_;
 }
 
+bool TestLifecycleUnit::Freeze() {
+  return false;
+}
+
+bool TestLifecycleUnit::Unfreeze() {
+  return false;
+}
+
 bool TestLifecycleUnit::Discard(DiscardReason discard_reason) {
   return false;
 }

chrome/browser/resource_coordinator/test_lifecycle_unit.h

@@ -33,12 +33,13 @@ class TestLifecycleUnit : public LifecycleUnitBase {
   content::Visibility GetVisibility() const override;
   LifecycleUnitLoadingState GetLoadingState() const override;
   bool Load() override;
-  bool Freeze() override;
   int GetEstimatedMemoryFreedOnDiscardKB() const override;
   bool CanPurge() const override;
   bool CanFreeze(DecisionDetails* decision_details) const override;
   bool CanDiscard(DiscardReason reason,
                   DecisionDetails* decision_details) const override;
+  bool Freeze() override;
+  bool Unfreeze() override;
   bool Discard(DiscardReason discard_reason) override;
 
  private: