TabManager: Do not overkill when target memory to free is negative.

chrome/browser/memory/tab_manager_browsertest.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 "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 170 matching lines @@
   WindowedNotificationObserver back2(
       content::NOTIFICATION_NAV_ENTRY_COMMITTED,
       base::Bind(&ObserveNavEntryCommitted, GURL(chrome::kChromeUITermsURL)));
   chrome::GoBack(browser(), WindowOpenDisposition::CURRENT_TAB);
   back2.Wait();
   EXPECT_FALSE(chrome::CanGoBack(browser()));
   EXPECT_TRUE(chrome::CanGoForward(browser()));
 }
 
 // On Linux, memory pressure listener is not implemented yet.
-#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_CHROMEOS)
+#if defined(OS_WIN) || defined(OS_MACOSX)

[Georges Khalil, 2017/04/25 15:21:15]

Why are we disabling the test for CrOS here?

[cylee1, 2017/04/25 15:46:20]

It's what this CL fixes: 
on CrOS, it reads memory state (free memory, swap, etc) to figure out how much
memory to free. If it sees memory has been recovered to normal level since the
low memory signal had been raised, no tab is discarded. That's why this test
would fail - it no longer kills "at least" one tab.

TabManagerDelegate has its own test, so I just disabled the test here.

[Georges Khalil, 2017/04/25 15:47:41]

Got it, thanks.

 
 // Test that the MemoryPressureListener event is properly triggering a tab
 // discard upon |MEMORY_PRESSURE_LEVEL_CRITICAL| event.
 IN_PROC_BROWSER_TEST_F(TabManagerTest, OomPressureListener) {
   TabManager* tab_manager = g_browser_process->GetTabManager();
 
   // Disable the protection of recent tabs.
   tab_manager->set_minimum_protection_time_for_tests(
       base::TimeDelta::FromMinutes(0));
 
@@ skipping 376 matching lines @@
   ASSERT_TRUE(tab1_contents_data->is_purged());
   ASSERT_TRUE(tab2_contents_data->is_purged());
   ASSERT_FALSE(tab3_contents_data->is_purged());
 
   tsm->CloseAllTabs();
 }
 
 }  // namespace memory
 
 #endif  // OS_WIN || OS_MAXOSX || OS_LINUX