cros: Protect app windows from out-of-memory kills

chrome/browser/chromeos/oom_priority_manager.cc

 // Copyright (c) 2012 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/chromeos/oom_priority_manager.h"
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
@@ skipping 107 matching lines @@
   // deleting us when we're still working.
   Release();
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // OomPriorityManager
 
 OomPriorityManager::TabStats::TabStats()
-  : is_pinned(false),
+  : is_app(false),
+    is_pinned(false),
     is_selected(false),
     is_discarded(false),
     sudden_termination_allowed(false),
     renderer_handle(0),
     tab_contents_id(0) {
 }
 
 OomPriorityManager::TabStats::~TabStats() {
 }
 
@@ skipping 44 matching lines @@
   titles.reserve(stats.size());
   TabStatsList::iterator it = stats.begin();
   for ( ; it != stats.end(); ++it) {
     string16 str;
     str.reserve(4096);
     str += it->title;
     str += ASCIIToUTF16(" (");
     int score = pid_to_oom_score_[it->renderer_handle];
     str += base::IntToString16(score);
     str += ASCIIToUTF16(")");
-    str += ASCIIToUTF16(it->sudden_termination_allowed ? " sudden_ok " : "");

[Greg Spencer (Chromium), 2012/08/21 18:51:42]

Did you mean to remove the output of the sudden_termination_allowed_ flag?

Actually, it seems we don't do anything at all with that flag: can we remove it
completely?

+    str += ASCIIToUTF16(it->is_app ? " app" : "");
+    str += ASCIIToUTF16(it->is_pinned ? " pinned" : "");
     str += ASCIIToUTF16(it->is_discarded ? " discarded" : "");
     titles.push_back(str);
   }
   return titles;
 }
 
 // TODO(jamescook): This should consider tabs with references to other tabs,
 // such as tabs created with JavaScript window.open().  We might want to
 // discard the entire set together, or use that in the priority computation.
 bool OomPriorityManager::DiscardTab() {
@@ skipping 103 matching lines @@
 bool OomPriorityManager::CompareTabStats(TabStats first,
                                          TabStats second) {
   // Being currently selected is most important.
   if (first.is_selected != second.is_selected)
     return first.is_selected == true;
 
   // Being pinned is second most important.
   if (first.is_pinned != second.is_pinned)
     return first.is_pinned == true;
 
+  // Being an app is important too, as you're the only visible surface in the
+  // window and we don't want to discard that.
+  if (first.is_app != second.is_app)
+    return first.is_app == true;
+
   // TODO(jamescook): Incorporate sudden_termination_allowed into the sort
   // order.  We don't do this now because pages with unload handlers set
   // sudden_termination_allowed false, and that covers too many common pages
   // with ad networks and statistics scripts.  Ideally we would like to check
   // for beforeUnload handlers, which are likely to present a dialog asking
   // if the user wants to discard state.  crbug.com/123049
 
   // Being more recently selected is more important.
   return first.last_selected > second.last_selected;
 }
@@ skipping 101 matching lines @@
 OomPriorityManager::TabStatsList OomPriorityManager::GetTabStatsOnUIThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   TabStatsList stats_list;
   stats_list.reserve(32);  // 99% of users have < 30 tabs open
   bool browser_active = true;
   for (BrowserList::const_reverse_iterator browser_iterator =
            BrowserList::begin_last_active();
        browser_iterator != BrowserList::end_last_active();
        ++browser_iterator) {
     Browser* browser = *browser_iterator;
+    bool is_browser_for_app = browser->is_app();
     const TabStripModel* model = browser->tab_strip_model();
     for (int i = 0; i < model->count(); i++) {
       WebContents* contents = model->GetTabContentsAt(i)->web_contents();
       if (!contents->IsCrashed()) {
         TabStats stats;
+        stats.is_app = is_browser_for_app;
         stats.is_pinned = model->IsTabPinned(i);
         stats.is_selected = browser_active && model->IsTabSelected(i);
         stats.is_discarded = model->IsTabDiscarded(i);
         stats.sudden_termination_allowed =
             contents->GetRenderProcessHost()->SuddenTerminationAllowed();
         stats.last_selected = contents->GetLastSelectedTime();
         stats.renderer_handle = contents->GetRenderProcessHost()->GetHandle();
         stats.title = contents->GetTitle();
         stats.tab_contents_id = IdFromTabContents(contents);
         stats_list.push_back(stats);
@@ skipping 48 matching lines @@
         content::ZygoteHost::GetInstance()->AdjustRendererOOMScore(
             iterator->renderer_handle, score);
         pid_to_oom_score_[iterator->renderer_handle] = score;
       }
       priority += priority_increment;
     }
   }
 }
 
 }  // namespace chromeos