Create Memory Helper for memory warnings

ios/chrome/app/application_delegate/memory_recovery_helper_unittest.mm

+// Copyright 2016 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.
+
+#import "base/mac/bind_objc_block.h"

[Eugene But (OOO till 7-30), 2016/05/18 15:55:08]

s/import/include

https://engdoc.corp.google.com/eng/doc/objcguide.xml?showone=Order_of_Include...

[gambard, 2016/05/19 09:35:04]

Done.

+#include "base/mac/scoped_nsobject.h"

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

s/include/import

[gambard, 2016/05/19 09:35:04]

Done.

+#include "base/memory/memory_pressure_listener.h"
+#include "base/threading/thread.h"
+#import "ios/chrome/browser/metrics/previous_session_info.h"
+#import "ios/chrome/app/application_delegate/memory_recovery_helper.h"

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

This import should go first, then libraries, then the rest of includes.
https://engdoc.corp.google.com/eng/doc/objcguide.xml?showone=Order_of_Include...

[gambard, 2016/05/19 09:35:03]

Done.

+#include "testing/platform_test.h"
+
+namespace {

[Eugene But (OOO till 7-30), 2016/05/18 15:55:08]

NIT: There is no need to put tests into anonymous namespace (there was a related
discussion on Chromium-dev and if you want I can find it). However I do
understand that most of our tests actually live in an anonymous namespace. 

[gambard, 2016/05/19 09:35:04]

Done.

+class MemoryRecoveryHelperTest : public PlatformTest {
+ protected:
+  MemoryRecoveryHelperTest() {
+    // Set up |memory_pressure_listener_| to invoke |OnMemoryPressure| which
+    // will store the memory pressure level sent to the callback in
+    // |memory_pressure_level_| so that tests can verify the level is correct.
+    memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
+        &MemoryRecoveryHelperTest::OnMemoryPressure, base::Unretained(this))));
+    memory_pressure_level_ =
+        base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE;
+  }
+
+  base::MemoryPressureListener::MemoryPressureLevel GetMemoryPressureLevel() {
+    return memory_pressure_level_;
+  }
+
+  MemoryRecoveryHelper* GetMemoryHelper() {
+    if (!memory_helper_.get()) {

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

Drop |.get()|

[gambard, 2016/05/19 09:35:04]

Done.

+      memory_helper_.reset([[MemoryRecoveryHelper alloc] init]);
+    }
+    return memory_helper_.get();
+  }
+
+  // Callback for |memory_pressure_listener_|.
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+    memory_pressure_level_ = memory_pressure_level;
+    message_loop_.QuitWhenIdle();
+  }
+
+  base::MessageLoop& message_loop() { return message_loop_; }
+
+ private:
+  base::MessageLoop message_loop_;
+  base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level_;
+  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
+  base::scoped_nsobject<MemoryRecoveryHelper> memory_helper_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryRecoveryHelperTest);
+};
+
+// Invokes resetForegroundMemoryWarningCount and verifies the
+// foregroundMemoryWarningCount is setted to 0

[Eugene But (OOO till 7-30), 2016/05/18 15:55:07]

Optional NIT: finish the comments with full stop

[gambard, 2016/05/19 09:35:04]

Done.

+TEST_F(MemoryRecoveryHelperTest, VerifyForegroundMemoryWarningCountReset) {
+  // Setup
+  MemoryRecoveryHelper* memoryHelper = GetMemoryHelper();
+  [memoryHelper handleMemoryPressure];
+  int previousForegroundMemoryWarningCount =

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

NIT: Drop this variable and just use EXPECT_TRUE (or even better ASSERT_TRUE,
because it is a precondition):

EXPECT_TRUE(memoryHelper.foregroundMemoryWarningCount != 0);

[gambard, 2016/05/19 09:35:04]

Done.

+      memoryHelper.foregroundMemoryWarningCount;
+
+  // Action
+  [memoryHelper resetForegroundMemoryWarningCount];
+
+  // Test
+  EXPECT_TRUE(previousForegroundMemoryWarningCount != 0);
+  EXPECT_EQ(0, memoryHelper.foregroundMemoryWarningCount);
+}
+
+// Invokes applicationDidReceiveMemoryWarning and verifies the memory pressure
+// callback (i.e. MainControllerTest::OnMemoryPressure) is invoked.
+TEST_F(MemoryRecoveryHelperTest, VerifyApplicationDidReceiveMemoryWarning) {
+  MemoryRecoveryHelper* memoryHelper = GetMemoryHelper();

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

Optional NIT: Drop this variable

[gambard, 2016/05/19 09:35:04]

Done.

+  [memoryHelper handleMemoryPressure];
+  message_loop().Run();
+  EXPECT_EQ(base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            GetMemoryPressureLevel());
+}
+
+// Invokes applicationDidReceiveMemoryWarning and verifies the flags (i.e.
+// breakpad_helper and NSUserDefaults) are set
+TEST_F(MemoryRecoveryHelperTest, VerifyHelperDidSetMemoryWarningFlags) {
+  // Setup
+  MemoryRecoveryHelper* memoryHelper = GetMemoryHelper();

[Eugene But (OOO till 7-30), 2016/05/18 15:55:09]

Drop this variable, it is used only once and GetMemoryHelper() used many times.

[gambard, 2016/05/19 09:35:04]

Done.

+  [[PreviousSessionInfo sharedInstance] beginRecordingCurrentSession];
+  [[PreviousSessionInfo sharedInstance] resetMemoryWarningFlag];
+  int foregroundMemoryWarningCountBeforeWarning =
+      GetMemoryHelper().foregroundMemoryWarningCount;
+
+  BOOL memoryWarningFlagBeforeAlert = [[NSUserDefaults standardUserDefaults]
+      boolForKey:previous_session_info_constants::

[Eugene But (OOO till 7-30), 2016/05/18 15:55:07]

Optional NIT: Could you please add using
previous_session_info_constants::kDidSeeMemoryWarningShortlyBeforeTerminating to
make this more readable.

[gambard, 2016/05/19 09:35:03]

Done.

+                     kDidSeeMemoryWarningShortlyBeforeTerminating];
+
+  // Action
+  [memoryHelper handleMemoryPressure];
+
+  // Tests
+  EXPECT_TRUE([[NSUserDefaults standardUserDefaults]
+      boolForKey:previous_session_info_constants::
+                     kDidSeeMemoryWarningShortlyBeforeTerminating]);
+  EXPECT_FALSE(memoryWarningFlagBeforeAlert);
+  EXPECT_EQ(foregroundMemoryWarningCountBeforeWarning + 1,
+            GetMemoryHelper().foregroundMemoryWarningCount);
+}
+}  // namespace