Enable TabManager to kill foreground Android apps.

chrome/browser/memory/tab_manager_delegate_chromeos.cc

 // Copyright 2015 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 "chrome/browser/memory/tab_manager_delegate_chromeos.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <map>
@@ skipping 575 matching lines @@
   const std::vector<TabManagerDelegate::Candidate> candidates =
       GetSortedCandidates(tab_list, arc_processes);
 
   int target_memory_to_free_kb = mem_stat_->TargetMemoryToFreeKB();
   // Kill processes until the estimated amount of freed memory is sufficient to
   // bring the system memory back to a normal level.
   // The list is sorted by descending importance, so we go through the list
   // backwards.
   for (auto it = candidates.rbegin(); it != candidates.rend(); ++it) {
     VLOG(3) << "Target memory to free: " << target_memory_to_free_kb << " KB";
-    // Never kill selected tab or Android foreground app, regardless whether
-    // they're in the active window. Since the user experience would be bad.
+    // Never kill selected tab to align with the behavior in other platforms.
+    // Note that non-focused Android apps are prone to be killed, however,
+    // regardless of their visibility.
     ProcessType process_type = it->process_type();
-    if (process_type == ProcessType::VISIBLE_APP ||
-        process_type == ProcessType::FOCUSED_APP ||
+    if (process_type == ProcessType::FOCUSED_APP ||
         process_type == ProcessType::FOCUSED_TAB) {
       VLOG(2) << "Skipped killing " << *it;
       continue;
     }
     if (it->app()) {
       int estimated_memory_freed_kb =
           mem_stat_->EstimatedMemoryFreedKB(it->app()->pid());
       if (KillArcProcess(it->app()->nspid())) {
         target_memory_to_free_kb -= estimated_memory_freed_kb;
         MemoryKillsMonitor::LogLowMemoryKill("APP", estimated_memory_freed_kb);
@@ skipping 112 matching lines @@
     }
     priority += priority_increment;
   }
 
   if (oom_scores_to_change.size())
     GetDebugDaemonClient()->SetOomScoreAdj(
         oom_scores_to_change, base::Bind(&OnSetOomScoreAdj));
 }
 
 }  // namespace memory