Revert of Release unused web views when under memory pressure. (patchset #5 id:100001 of https://codereview.chromium.org/1708643002/ )

Reason for revert:
TypedUrlSyncableServiceTest.DeleteUrlAndVisits fails on Win and CROS ASAN:

Win:
https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/46063/steps/components_unittests/logs/TypedUrlSyncableServiceTest.DeleteUrlAndVisits

https://build.chromium.org/p/chromium.win/buildstatus?builder=Win7%20Tests%20%28dbg%29%281%29&number=46064

https://build.chromium.org/p/chromium.win/buildstatus?builder=Win7%20Tests%20%28dbg%29%281%29&number=46063

CROS ASAN:

https://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/builds/9861/steps/components_unittests/logs/TypedUrlSyncableServiceTest.DeleteUrlAndVisits

https://build.chromium.org/p/chromium.memory/buildstatus?builder=Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29&number=9861

Original issue's description:
> Release unused web views when under memory pressure.
>
> AccountConsistencyService and GaiaAuthFetcherIOS both use web views
> internally to manipulate cookies. Once allocated, those web views were
> never released to avoid having to re-allocate them later (which is
> expensive).
>
> Those web views are now released when they are unused and the app is
> under memory pressure.
>
> BUG=587487
>
> Committed: https://crrev.com/8a730bd4d690e5c9f9b3639cbedec5b5dc2bbe12
> Cr-Commit-Position: refs/heads/master@{#376431}

TBR=msarda@chromium.org,zea@chromium.org,bzanotti@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=587487

Review URL: https://codereview.chromium.org/1713973003

Cr-Commit-Position: refs/heads/master@{#376445}

3 files changed, 0 insertions, 55 deletions

diff --git a/ios/chrome/browser/signin/gaia_auth_fetcher_ios.mm b/ios/chrome/browser/signin/gaia_auth_fetcher_ios.mm
index 2790a68..a8c3da6 100644
--- a/ios/chrome/browser/signin/gaia_auth_fetcher_ios.mm
+++ b/ios/chrome/browser/signin/gaia_auth_fetcher_ios.mm
@@ -6,8 +6,6 @@
 
 #import <WebKit/WebKit.h>
 
-#include "base/bind.h"
-#include "base/bind_helpers.h"
 #include "base/json/string_escape.h"
 #include "base/logging.h"
 #import "base/mac/foundation_util.h"
@@ -212,8 +210,6 @@ GaiaAuthFetcherIOSBridge::GaiaAuthFetcherIOSBridge(
     web::BrowserState* browser_state)
     : browser_state_(browser_state), fetcher_(fetcher), request_() {
   web::BrowserState::GetActiveStateManager(browser_state_)->AddObserver(this);
-  memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
-      &GaiaAuthFetcherIOSBridge::OnMemoryPressure, base::Unretained(this))));
 }
 
 GaiaAuthFetcherIOSBridge::~GaiaAuthFetcherIOSBridge() {
@@ -315,16 +311,6 @@ void GaiaAuthFetcherIOSBridge::OnInactive() {
   ResetWKWebView();
 }
 
-void GaiaAuthFetcherIOSBridge::OnMemoryPressure(
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  bool is_memory_pressure_critical =
-      (level == base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
-  if (is_memory_pressure_critical && !request_.pending) {
-    // |web_view_| isn't being used, release it.
-    ResetWKWebView();
-  }
-}
-
 #pragma mark - GaiaAuthFetcherIOS definition
 
 GaiaAuthFetcherIOS::GaiaAuthFetcherIOS(GaiaAuthConsumer* consumer,
diff --git a/ios/chrome/browser/signin/gaia_auth_fetcher_ios_private.h b/ios/chrome/browser/signin/gaia_auth_fetcher_ios_private.h
index d7097c6..0fd1a41 100644
--- a/ios/chrome/browser/signin/gaia_auth_fetcher_ios_private.h
+++ b/ios/chrome/browser/signin/gaia_auth_fetcher_ios_private.h
@@ -9,7 +9,6 @@
 
 #import "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
-#include "base/memory/memory_pressure_listener.h"
 #include "ios/web/public/active_state_manager.h"
 
 class GaiaAuthFetcherIOS;
@@ -93,10 +92,6 @@ class GaiaAuthFetcherIOSBridge : web::ActiveStateManager::Observer {
   void OnActive() override;
   void OnInactive() override;
 
-  // Memory pressure callback.
-  void OnMemoryPressure(
-      base::MemoryPressureListener::MemoryPressureLevel level);
-
   // Browser state associated with the bridge, used to create WKWebViews.
   web::BrowserState* browser_state_;
   // Fetcher owning this bridge.
@@ -109,9 +104,6 @@ class GaiaAuthFetcherIOSBridge : web::ActiveStateManager::Observer {
   // Web view used to do the network requests.
   base::scoped_nsobject<WKWebView> web_view_;
 
-  // Listens to memory pressure notifications.
-  scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
-
   DISALLOW_COPY_AND_ASSIGN(GaiaAuthFetcherIOSBridge);
 };
 
diff --git a/ios/chrome/browser/signin/gaia_auth_fetcher_ios_unittest.mm b/ios/chrome/browser/signin/gaia_auth_fetcher_ios_unittest.mm
index fea9c49..822ac27 100644
--- a/ios/chrome/browser/signin/gaia_auth_fetcher_ios_unittest.mm
+++ b/ios/chrome/browser/signin/gaia_auth_fetcher_ios_unittest.mm
@@ -72,7 +72,6 @@ class GaiaAuthFetcherIOSTest : public PlatformTest {
     return gaia_auth_fetcher_->bridge_.get();
   }
 
-  bool HasWKWebView() { return gaia_auth_fetcher_->bridge_->web_view_; }
   id GetMockWKWebView() { return gaia_auth_fetcher_->bridge_->GetWKWebView(); }
 
   web::TestWebThreadBundle thread_bundle_;
@@ -192,35 +191,3 @@ TEST_F(GaiaAuthFetcherIOSTest, StopOnInactiveReFetchOnActive) {
   web::BrowserState::GetActiveStateManager(&browser_state_)->SetActive(true);
   EXPECT_OCMOCK_VERIFY(GetMockWKWebView());
 }
-
-// Tests that the web view is not released when receiving a memory pressure
-// notification if it is being used.
-TEST_F(GaiaAuthFetcherIOSTest, UsedWebViewNotReleasedOnMemoryPressure) {
-  [static_cast<WKWebView*>([GetMockWKWebView() expect])
-      loadRequest:[OCMArg any]];
-  gaia_auth_fetcher_->StartMergeSession("uber_token", "");
-
-  base::MemoryPressureListener::NotifyMemoryPressure(
-      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
-  base::RunLoop().RunUntilIdle();
-
-  EXPECT_TRUE(HasWKWebView());
-  EXPECT_OCMOCK_VERIFY(GetMockWKWebView());
-}
-
-// Tests that the web view is correctly released when receiving a memory
-// pressure notification if it is not being used.
-TEST_F(GaiaAuthFetcherIOSTest, UnusedWebViewReleasedOnMemoryPressure) {
-  EXPECT_CALL(consumer_, OnMergeSessionSuccess("data")).Times(1);
-  [static_cast<WKWebView*>([[GetMockWKWebView() expect] andDo:^(NSInvocation*) {
-    GetBridge()->URLFetchSuccess("data");
-  }]) loadRequest:[OCMArg any]];
-  gaia_auth_fetcher_->StartMergeSession("uber_token", "");
-
-  base::MemoryPressureListener::NotifyMemoryPressure(
-      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
-  base::RunLoop().RunUntilIdle();
-
-  EXPECT_FALSE(HasWKWebView());
-  EXPECT_OCMOCK_VERIFY(GetMockWKWebView());
-}