[Android] Add memory upper threshold control for real time URL lookup.

In order to control real time URL lookup via high-end and low-end
groups, add a memory upper threshold control.

This change will make it easier for finch configuration, see:
go/wmpfd

Bug: 1014202
Change-Id: I639153c9baac73cd8bfcdaff3a82c020237a6c4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2092697
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748468}

components/safe_browsing/core/realtime/policy_engine.cc

@@ -26,7 +26,9 @@
 namespace safe_browsing {
 
 #if defined(OS_ANDROID)
-const int kDefaultMemoryThresholdMb = 4096;
+const int kDefaultMemoryLowerThresholdMb = 4096;
+// By default, the upper threshold shouldn't be in effect.
+const int kDefaultMemoryUpperThresholdMb = INT_MAX;
 #endif
 
 // static
@@ -35,12 +37,17 @@ bool RealTimePolicyEngine::IsUrlLookupEnabled() {
     return false;
 #if defined(OS_ANDROID)
   // On Android, performs real time URL lookup only if
-  // |kRealTimeUrlLookupEnabled| is enabled, and system memory is larger than
-  // threshold.
-  int memory_threshold_mb = base::GetFieldTrialParamByFeatureAsInt(
-      kRealTimeUrlLookupEnabled, kRealTimeUrlLookupMemoryThresholdMb,
-      kDefaultMemoryThresholdMb);
-  return base::SysInfo::AmountOfPhysicalMemoryMB() >= memory_threshold_mb;
+  // |kRealTimeUrlLookupEnabled| is enabled, and system memory is between the
+  // upper threshold and lower threshold.
+  int memory_lower_threshold_mb = base::GetFieldTrialParamByFeatureAsInt(
+      kRealTimeUrlLookupEnabled, kRealTimeUrlLookupMemoryLowerThresholdMb,
+      kDefaultMemoryLowerThresholdMb);
+  int memory_upper_threshold_mb = base::GetFieldTrialParamByFeatureAsInt(
+      kRealTimeUrlLookupEnabled, kRealTimeUrlLookupMemoryUpperThresholdMb,
+      kDefaultMemoryUpperThresholdMb);
+  return base::SysInfo::AmountOfPhysicalMemoryMB() >=
+             memory_lower_threshold_mb &&
+         base::SysInfo::AmountOfPhysicalMemoryMB() <= memory_upper_threshold_mb;
 #else
   return true;
 #endif

components/safe_browsing/core/realtime/policy_engine.h

@@ -20,9 +20,12 @@ enum class ResourceType;
 #if defined(OS_ANDROID)
 // A parameter controlled by finch experiment.
 // On Android, performs real time URL lookup only if |kRealTimeUrlLookupEnabled|
-// is enabled, and system memory is larger than threshold.
-const char kRealTimeUrlLookupMemoryThresholdMb[] =
+// is enabled, and system memory is between the upper threshold and the lower
+// threshold.
+const char kRealTimeUrlLookupMemoryLowerThresholdMb[] =
     "SafeBrowsingRealTimeUrlLookupMemoryThresholdMb";
+const char kRealTimeUrlLookupMemoryUpperThresholdMb[] =
+    "SafeBrowsingRealTimeUrlLookupMemoryUpperThresholdMb";
 #endif
 
 // This class implements the logic to decide whether the real time lookup

components/safe_browsing/core/realtime/policy_engine_unittest.cc

@@ -59,12 +59,12 @@ class RealTimePolicyEngineTest : public PlatformTest {
 TEST_F(RealTimePolicyEngineTest, TestCanPerformFullURLLookup_LargeMemorySize) {
   base::test::ScopedFeatureList feature_list;
   int system_memory_size = base::SysInfo::AmountOfPhysicalMemoryMB();
-  int memory_size_threshold = system_memory_size - 1;
+  int memory_size_lower_threshold = system_memory_size - 1;
   feature_list.InitWithFeaturesAndParameters(
       /* enabled_features */ {{kRealTimeUrlLookupEnabled,
-                               {{kRealTimeUrlLookupMemoryThresholdMb,
+                               {{kRealTimeUrlLookupMemoryLowerThresholdMb,
                                  base::NumberToString(
-                                     memory_size_threshold)}}}},
+                                     memory_size_lower_threshold)}}}},
       /* disabled_features */ {});
   pref_service_.SetUserPref(
       unified_consent::prefs::kUrlKeyedAnonymizedDataCollectionEnabled,
@@ -72,15 +72,32 @@ TEST_F(RealTimePolicyEngineTest, TestCanPerformFullURLLookup_LargeMemorySize) {
   EXPECT_TRUE(CanPerformFullURLLookup(/* is_off_the_record */ false));
 }
 
+TEST_F(RealTimePolicyEngineTest,
+       TestCanPerformFullURLLookup_LargeMemorySizeExceedUpperThreshold) {
+  base::test::ScopedFeatureList feature_list;
+  int system_memory_size = base::SysInfo::AmountOfPhysicalMemoryMB();
+  int memory_size_upper_threshold = system_memory_size - 1;
+  feature_list.InitWithFeaturesAndParameters(
+      /* enabled_features */ {{kRealTimeUrlLookupEnabled,
+                               {{kRealTimeUrlLookupMemoryUpperThresholdMb,
+                                 base::NumberToString(
+                                     memory_size_upper_threshold)}}}},
+      /* disabled_features */ {});
+  pref_service_.SetUserPref(
+      unified_consent::prefs::kUrlKeyedAnonymizedDataCollectionEnabled,
+      std::make_unique<base::Value>(true));
+  EXPECT_FALSE(CanPerformFullURLLookup(/* is_off_the_record */ false));
+}
+
 TEST_F(RealTimePolicyEngineTest, TestCanPerformFullURLLookup_SmallMemorySize) {
   base::test::ScopedFeatureList feature_list;
   int system_memory_size = base::SysInfo::AmountOfPhysicalMemoryMB();
-  int memory_size_threshold = system_memory_size + 1;
+  int memory_size_lower_threshold = system_memory_size + 1;
   feature_list.InitWithFeaturesAndParameters(
       /* enabled_features */ {{kRealTimeUrlLookupEnabled,
-                               {{kRealTimeUrlLookupMemoryThresholdMb,
+                               {{kRealTimeUrlLookupMemoryLowerThresholdMb,
                                  base::NumberToString(
-                                     memory_size_threshold)}}}},
+                                     memory_size_lower_threshold)}}}},
       /* disabled_features */ {});
   pref_service_.SetUserPref(
       unified_consent::prefs::kUrlKeyedAnonymizedDataCollectionEnabled,
@@ -139,11 +156,12 @@ TEST_F(RealTimePolicyEngineTest,
   base::test::ScopedFeatureList feature_list;
 #if defined(OS_ANDROID)
   int system_memory_size = base::SysInfo::AmountOfPhysicalMemoryMB();
-  int memory_size_threshold = system_memory_size - 1;
+  int memory_size_lower_threshold = system_memory_size - 1;
   feature_list.InitWithFeaturesAndParameters(
       /* enabled_features */ {{kRealTimeUrlLookupEnabled,
-                               {{kRealTimeUrlLookupMemoryThresholdMb,
-                                 base::NumberToString(memory_size_threshold)}}},
+                               {{kRealTimeUrlLookupMemoryLowerThresholdMb,
+                                 base::NumberToString(
+                                     memory_size_lower_threshold)}}},
                               {kRealTimeUrlLookupEnabledWithToken, {}}},
       /* disabled_features */ {});
 #else

components/safe_browsing/core/realtime/url_lookup_service_unittest.cc

@@ -133,14 +133,15 @@ class RealTimeUrlLookupServiceTest : public PlatformTest {
         std::make_unique<base::Value>(true));
 #if defined(OS_ANDROID)
     int system_memory_size = base::SysInfo::AmountOfPhysicalMemoryMB();
-    int memory_size_threshold = system_memory_size - 1;
+    int memory_size_lower_threshold = system_memory_size - 1;
     if (is_with_token_enabled) {
       feature_list_.InitWithFeaturesAndParameters(
           /* enabled_features */ {{kRealTimeUrlLookupEnabled,
-                                   { {
-                                     kRealTimeUrlLookupMemoryThresholdMb,
-                                     base::NumberToString(memory_size_threshold)
-                                   } }},
+                                   {
+                                     { kRealTimeUrlLookupMemoryLowerThresholdMb,
+                                       base::NumberToString(
+                                           memory_size_lower_threshold) }
+                                   }},
                                   { kRealTimeUrlLookupEnabledWithToken,
                                     {} }},
           /* disabled_features */ {});
@@ -149,8 +150,8 @@ class RealTimeUrlLookupServiceTest : public PlatformTest {
           /* enabled_features */ {{
             kRealTimeUrlLookupEnabled,
             {
-              { kRealTimeUrlLookupMemoryThresholdMb,
-                base::NumberToString(memory_size_threshold) }
+              { kRealTimeUrlLookupMemoryLowerThresholdMb,
+                base::NumberToString(memory_size_lower_threshold) }
             }
           }},
           /* disabled_features */ {});