Update default policy for memory coordinator

content/browser/memory/memory_coordinator_default_policy.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/memory/memory_coordinator_default_policy.h"
 
 namespace content {
 
-namespace {
-
-const int kDefaultBackgroundChildPurgeCandidatePeriodSeconds = 30;
-
-MemoryState CalculateMemoryStateForProcess(MemoryCondition condition) {
-  if (condition == MemoryCondition::CRITICAL)
-    return MemoryState::THROTTLED;
-  return MemoryState::NORMAL;
-}
-
-}  // namespace
-
 MemoryCoordinatorDefaultPolicy::MemoryCoordinatorDefaultPolicy(
     MemoryCoordinatorImpl* coordinator)
     : coordinator_(coordinator) {
   DCHECK(coordinator_);
 }
 
 MemoryCoordinatorDefaultPolicy::~MemoryCoordinatorDefaultPolicy() {}
 
 void MemoryCoordinatorDefaultPolicy::OnCriticalCondition() {
+  // Just trigger tab discarding for now.
   coordinator_->DiscardTab();
-
-  // Prefer to purge memory from child processes than browser process because
-  // we prioritize the brower process.
-  if (TryToPurgeMemoryFromChildren(PurgeTarget::ALL))
-    return;
-
-  coordinator_->TryToPurgeMemoryFromBrowser();
 }
 
 void MemoryCoordinatorDefaultPolicy::OnConditionChanged(MemoryCondition prev,
-                                                        MemoryCondition next) {
-  DCHECK(prev != next);
-  if (next == MemoryCondition::NORMAL) {
-    // Set NORMAL state to all clients/processes.
-    coordinator_->SetBrowserMemoryState(MemoryState::NORMAL);
-    SetMemoryStateToAllChildren(MemoryState::NORMAL);
-  } else if (next == MemoryCondition::CRITICAL) {
-    // Set THROTTLED state to all clients/processes.
-    coordinator_->SetBrowserMemoryState(MemoryState::THROTTLED);
-    SetMemoryStateToAllChildren(MemoryState::THROTTLED);
-  }
-}
+                                                        MemoryCondition next) {}
 
 void MemoryCoordinatorDefaultPolicy::OnChildVisibilityChanged(
     int render_process_id,
-    bool is_visible) {
-  auto iter = coordinator_->children().find(render_process_id);
-  if (iter == coordinator_->children().end())
-    return;
-
-  iter->second.is_visible = is_visible;
-  if (!is_visible) {
-    // A backgrounded process becomes a candidate for purging memory when
-    // the process remains backgrounded for a certian period of time.
-    iter->second.can_purge_after =
-        coordinator_->NowTicks() +
-        base::TimeDelta::FromSeconds(
-            kDefaultBackgroundChildPurgeCandidatePeriodSeconds);
-  }
-  MemoryState new_state =
-      CalculateMemoryStateForProcess(coordinator_->GetMemoryCondition());
-  coordinator_->SetChildMemoryState(render_process_id, new_state);
-}
-
-void MemoryCoordinatorDefaultPolicy::SetMemoryStateToAllChildren(
-    MemoryState state) {
-  // It's OK to call SetChildMemoryState() unconditionally because it checks
-  // whether this state transition is valid.
-  for (auto& iter : coordinator_->children())
-    coordinator_->SetChildMemoryState(iter.first, state);
-}
-
-bool MemoryCoordinatorDefaultPolicy::TryToPurgeMemoryFromChildren(
-    PurgeTarget target) {
-  // TODO(bashi): Better to sort child processes based on their priorities.
-  for (auto& iter : coordinator_->children()) {
-    if (iter.second.is_visible && target == PurgeTarget::BACKGROUNDED)
-      continue;
-    if (coordinator_->TryToPurgeMemoryFromChild(iter.first))
-      return true;
-  }
-  return false;
-}
+    bool is_visible) {}
 
 }  // namespace content