Add memory pressure monitor for Linux.

components/memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc

Index: components/memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc
diff --git a/components/memory_pressure/direct_memory_pressure_calculator_win_unittest.cc b/components/memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc
similarity index 76%
copy from components/memory_pressure/direct_memory_pressure_calculator_win_unittest.cc
copy to components/memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc
index cce65a405e5493ff82a6a7a743979a6c35d36c32..52c922c72b56bf95df396a01f5b7bfb5468ebd8c 100644
--- a/components/memory_pressure/direct_memory_pressure_calculator_win_unittest.cc
+++ b/components/memory_pressure/direct_memory_pressure_calculator_linux_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/memory_pressure/direct_memory_pressure_calculator_win.h"
+#include "components/memory_pressure/direct_memory_pressure_calculator_linux.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -11,6 +11,7 @@ namespace memory_pressure {
 namespace {
 
 static const int kKBperMB = 1024;
+static const int kTotalMemoryInMB = 4096;
 
 }  // namespace
 
@@ -19,13 +20,13 @@ static const int kKBperMB = 1024;
 class TestDirectMemoryPressureCalculator
     : public DirectMemoryPressureCalculator {
  public:
-  explicit TestDirectMemoryPressureCalculator(bool large_memory)
+  explicit TestDirectMemoryPressureCalculator()
       : DirectMemoryPressureCalculator(20, 10) {
     // The values passed to the MemoryPressureCalculator constructor are dummy
     // values that are immediately overwritten by InferTresholds.
 
-    // Generate a plausible amount of memory.
-    mem_info_.total = GenerateTotalMemoryMb(large_memory) * kKBperMB;
+    // Simulate 4GB of RAM.
+    mem_info_.total = kTotalMemoryInMB * kKBperMB;
 
     // Run InferThresholds using the test fixture's GetSystemMemoryStatus.
     InferThresholds();
@@ -39,17 +40,6 @@ class TestDirectMemoryPressureCalculator
     mem_info_.total = total_memory_mb * kKBperMB;
   }
 
-  // Generates an amount of total memory that is consistent with the requested
-  // memory model.
-  static int GenerateTotalMemoryMb(bool large_memory) {
-    int total_mb = 64;
-    while (total_mb < kLargeMemoryThresholdMb)
-      total_mb *= 2;
-    if (large_memory)
-      return total_mb * 2;
-    return total_mb / 2;
-  }
-
   // Sets up the memory status to reflect the provided absolute memory left.
   void SetMemoryFree(int phys_left_mb) {
     // |total| is set in the constructor and not modified.
@@ -125,30 +115,15 @@ class DirectMemoryPressureCalculatorTest : public testing::Test {
 // Tests the fundamental direct calculation of memory pressure with automatic
 // small-memory thresholds.
 TEST_F(DirectMemoryPressureCalculatorTest,
-       CalculateCurrentMemoryPressureLevelSmall) {
-  static const int kModerateMb =
-      DirectMemoryPressureCalculator::kSmallMemoryDefaultModerateThresholdMb;
-  static const int kCriticalMb =
-      DirectMemoryPressureCalculator::kSmallMemoryDefaultCriticalThresholdMb;
-
-  TestDirectMemoryPressureCalculator calc(false);  // Small-memory model.
-
-  EXPECT_EQ(kModerateMb, calc.moderate_threshold_mb());
-  EXPECT_EQ(kCriticalMb, calc.critical_threshold_mb());
-
-  ASSERT_NO_FATAL_FAILURE(CalculateCurrentPressureLevelTest(&calc));
-}
+       CalculateCurrentMemoryPressureLevel) {
+  TestDirectMemoryPressureCalculator calc;
 
-// Tests the fundamental direct calculation of memory pressure with automatic
-// large-memory thresholds.
-TEST_F(DirectMemoryPressureCalculatorTest,
-       CalculateCurrentMemoryPressureLevelLarge) {
   static const int kModerateMb =
-      DirectMemoryPressureCalculator::kLargeMemoryDefaultModerateThresholdMb;
+      (100 - DirectMemoryPressureCalculator::kDefaultModerateThresholdPc) *
+      kTotalMemoryInMB / 100;
   static const int kCriticalMb =
-      DirectMemoryPressureCalculator::kLargeMemoryDefaultCriticalThresholdMb;
-
-  TestDirectMemoryPressureCalculator calc(true);  // Large-memory model.
+      (100 - DirectMemoryPressureCalculator::kDefaultCriticalThresholdPc) *
+      kTotalMemoryInMB / 100;
 
   EXPECT_EQ(kModerateMb, calc.moderate_threshold_mb());
   EXPECT_EQ(kCriticalMb, calc.critical_threshold_mb());