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

chrome/browser/memory/tab_manager_browsertest.cc

Index: chrome/browser/memory/tab_manager_browsertest.cc
diff --git a/chrome/browser/memory/tab_manager_browsertest.cc b/chrome/browser/memory/tab_manager_browsertest.cc
index a5bad6babb5d26e83446c2ca9e57d70978de01bb..cfe3b3323e03245f5c8cdf54e97a60689cc62a7c 100644
--- a/chrome/browser/memory/tab_manager_browsertest.cc
+++ b/chrome/browser/memory/tab_manager_browsertest.cc
@@ -188,7 +188,7 @@ IN_PROC_BROWSER_TEST_F(TabManagerTest, TabManagerBasics) {
 }
 
 // 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.