[ios] Record metrics for stored CertificatePolicyCache size

This CL adds 2 new histogram. One for cert policy cache stored for Tab
and one for all Tabs.

Bug: 1140990
Change-Id: I03de0330759915974b4c89ceb7ee929d0118a53e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519153
Commit-Queue: Eugene But <eugenebut@chromium.org>
Auto-Submit: Eugene But <eugenebut@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824610}

ios/chrome/browser/sessions/session_service_ios.mm

@@ -245,6 +245,7 @@ NSString* const kSessionFileName =
 
   @try {
     NSError* error = nil;
+    size_t previous_cert_policy_bytes = web::GetCertPolicyBytesEncoded();
     NSData* sessionData = [NSKeyedArchiver archivedDataWithRootObject:session
                                                 requiringSecureCoding:NO
                                                                 error:&error];
@@ -255,8 +256,12 @@ NSString* const kSessionFileName =
       return;
     }
 
-    UMA_HISTOGRAM_COUNTS_100000("Session.WebStates.SerializedSize",
-                                sessionData.length / 1024);
+    base::UmaHistogramCounts100000(
+        "Session.WebStates.AllSerializedCertPolicyCachesSize",
+        web::GetCertPolicyBytesEncoded() - previous_cert_policy_bytes / 1024);
+
+    base::UmaHistogramCounts100000("Session.WebStates.SerializedSize",
+                                   sessionData.length / 1024);
 
     _taskRunner->PostTask(FROM_HERE, base::BindOnce(^{
                             [self performSaveSessionData:sessionData

ios/web/public/session/crw_session_certificate_policy_cache_storage.h

@@ -22,6 +22,11 @@ namespace web {
 extern NSString* const kCertificateSerializationKey;
 extern NSString* const kHostSerializationKey;
 extern NSString* const kStatusSerializationKey;
+
+// Total bytes serialized during CRWSessionCertificateStorage encoding since the
+// uptime.
+size_t GetCertPolicyBytesEncoded();
+
 }  // namespace web
 
 // A serializable representation of a certificate.

ios/web/session/crw_session_certificate_policy_cache_storage.mm

@@ -13,19 +13,12 @@
 #error "This file requires ARC support."
 #endif
 
-namespace web {
-// CRWSessionCertificateStorage serialization keys.
-NSString* const kCertificateSerializationKey = @"CertificateSerializationKey";
-NSString* const kHostSerializationKey = @"HostSerializationKey";
-NSString* const kStatusSerializationKey = @"StatusSerializationKey";
-
-// CRWSessionCertificatePolicyCacheStorage serialization keys.
-NSString* const kCertificateStoragesKey = @"kCertificateStoragesKey";
-NSString* const kCertificateStoragesDeprecatedKey = @"allowedCertificates";
-}  // namespace web
-
 namespace {
 
+// Total bytes serialized during CRWSessionCertificateStorage encoding since the
+// uptime.
+static size_t gBytesEncoded = 0;
+
 // The deprecated serialization technique serialized each certificate policy as
 // an NSArray, where the necessary information is stored at the following
 // indices.
@@ -51,6 +44,22 @@ scoped_refptr<net::X509Certificate> NSDataToCertificate(NSData* data) {
 
 }  // namespace
 
+namespace web {
+// CRWSessionCertificateStorage serialization keys.
+NSString* const kCertificateSerializationKey = @"CertificateSerializationKey";
+NSString* const kHostSerializationKey = @"HostSerializationKey";
+NSString* const kStatusSerializationKey = @"StatusSerializationKey";
+
+// CRWSessionCertificatePolicyCacheStorage serialization keys.
+NSString* const kCertificateStoragesKey = @"kCertificateStoragesKey";
+NSString* const kCertificateStoragesDeprecatedKey = @"allowedCertificates";
+
+size_t GetCertPolicyBytesEncoded() {
+  return gBytesEncoded;
+}
+
+}  // namespace web
+
 #pragma mark - CRWSessionCertificateStorage
 
 @interface CRWSessionCertificateStorage () {
@@ -110,11 +119,13 @@ scoped_refptr<net::X509Certificate> NSDataToCertificate(NSData* data) {
 }
 
 - (void)encodeWithCoder:(NSCoder*)aCoder {
-  [aCoder encodeObject:CertificateToNSData(_certificate.get())
-                forKey:web::kCertificateSerializationKey];
+  NSData* certData = CertificateToNSData(_certificate.get());
+  [aCoder encodeObject:certData forKey:web::kCertificateSerializationKey];
   [aCoder encodeObject:base::SysUTF8ToNSString(_host)
                 forKey:web::kHostSerializationKey];
   [aCoder encodeObject:@(_status) forKey:web::kStatusSerializationKey];
+
+  gBytesEncoded += certData.length + _host.size() + sizeof(_status);
 }
 
 #pragma mark Private

ios/web/session/crw_session_storage.mm

@@ -4,6 +4,7 @@
 
 #import "ios/web/public/session/crw_session_storage.h"
 
+#include "base/metrics/histogram_functions.h"
 #include "ios/web/common/features.h"
 #import "ios/web/navigation/nscoder_util.h"
 #import "ios/web/public/session/crw_session_certificate_policy_cache_storage.h"
@@ -106,8 +107,12 @@ NSString* const kLastCommittedItemIndexDeprecatedKey =
   [coder encodeInt:self.lastCommittedItemIndex
             forKey:kLastCommittedItemIndexKey];
   [coder encodeObject:self.itemStorages forKey:kItemStoragesKey];
+  size_t previous_cert_policy_bytes = web::GetCertPolicyBytesEncoded();
   [coder encodeObject:self.certPolicyCacheStorage
                forKey:kCertificatePolicyCacheStorageKey];
+  base::UmaHistogramCounts100000(
+      "Session.WebStates.SerializedCertPolicyCacheSize",
+      web::GetCertPolicyBytesEncoded() - previous_cert_policy_bytes / 1024);
   if (_userData)
     _userData->Encode(coder);
   web::UserAgentType userAgentType = _userAgentType;

tools/metrics/histograms/histograms_xml/session/histograms.xml

@@ -419,6 +419,17 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Session.WebStates.AllSerializedCertPolicyCachesSize"
+    units="KB" expires_after="2021-06-10">
+  <owner>eugenebut@chromium.org</owner>
+  <owner>gambard@chromium.org</owner>
+  <summary>
+    The size of all cert policy caches for all open tabs. Recorded when
+    SessionServiceIOS encodes the data, which happens on page loads, tab changes
+    and app backgrounding.
+  </summary>
+</histogram>
+
 <histogram name="Session.WebStates.ForwardItemsCountAfterNavigation"
     units="items" expires_after="2020-12-01">
   <obsolete>
@@ -475,6 +486,17 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Session.WebStates.SerializedCertPolicyCacheSize" units="KB"
+    expires_after="2021-06-10">
+  <owner>eugenebut@chromium.org</owner>
+  <owner>gambard@chromium.org</owner>
+  <summary>
+    The size of a single cert policy cache for one tab. Recorded when
+    CRWNavigationItemStorage encodes the data, which happens on page loads, tab
+    changes and app backgrounding.
+  </summary>
+</histogram>
+
 <histogram name="Session.WebStates.SerializedSize" units="KB"
     expires_after="2021-06-10">
   <owner>justincohen@chromium.org</owner>