Update ActivityLog detection to use previous values, hrefs.

chrome/browser/extensions/activity_log/activity_actions.cc

 // Copyright (c) 2013 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.
 
 #include "chrome/browser/extensions/activity_log/activity_actions.h"
 
 #include <algorithm>  // for std::find.
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 143 matching lines @@
 Action::InjectionType Action::DidInjectAd(
     rappor::RapporService* rappor_service) const {
   MaybeUploadUrl(rappor_service);
 
   // Currently, we do not have the list of ad networks, so we exit immediately
   // with NO_AD_INJECTION (unless the database has been set by a test).
   if (!AdNetworkDatabase::Get())
     return NO_AD_INJECTION;
 
   if (api_name_ == ad_injection_constants::kHtmlIframeSrcApiName ||
-      api_name_ == ad_injection_constants::kHtmlEmbedSrcApiName) {
+      api_name_ == ad_injection_constants::kHtmlEmbedSrcApiName ||
+      api_name_ == ad_injection_constants::kHtmlAnchorHrefApiName) {
     return CheckSrcModification();
   } else if (EndsWith(api_name_,
                       ad_injection_constants::kAppendChildApiSuffix,
                       true /* case senstive */)) {
     return CheckAppendChild();
   }
 
   return NO_AD_INJECTION;
 }
 
@@ skipping 236 matching lines @@
   if (!can_inject_ads)
     return;
 
   // Record the URL - an ad *may* have been injected.
   rappor_service->RecordSample(kExtensionAdInjectionRapporMetricName,
                                rappor::ETLD_PLUS_ONE_RAPPOR_TYPE,
                                host);
 }
 
 Action::InjectionType Action::CheckSrcModification() const {
-  bool injected_ad = arg_url_.is_valid() &&
-                     !arg_url_.is_empty() &&
-                     AdNetworkDatabase::Get()->IsAdNetwork(arg_url_);
-  return injected_ad ? INJECTION_NEW_AD : NO_AD_INJECTION;
+  const AdNetworkDatabase* database = AdNetworkDatabase::Get();
+
+  bool arg_url_valid = arg_url_.is_valid() && !arg_url_.is_empty();
+
+  GURL prev_url;
+  std::string prev_url_string;
+  if (args_.get() && args_->GetString(1u, &prev_url_string))
+    prev_url = GURL(prev_url_string);
+
+  bool prev_url_valid = prev_url.is_valid() && !prev_url.is_empty();
+
+  bool injected_ad = arg_url_valid && database->IsAdNetwork(arg_url_);
+  bool replaced_ad = prev_url_valid && database->IsAdNetwork(prev_url);
+
+  if (injected_ad && replaced_ad)
+    return INJECTION_REPLACED_AD;
+  if (injected_ad)
+    return INJECTION_NEW_AD;
+  if (replaced_ad)
+    return INJECTION_REMOVED_AD;
+
+  // If the extension replaced a valid URL with another valid URL for an iframe,
+  // embed, href, etc, then chances are it's ad injection (as there are few
+  // legitimate use cases for this). Log it as a likely one, which also helps
+  // us determine the effectiveness of our IsAdNetwork() recognition.
+  if (arg_url_valid && prev_url_valid)
+    return INJECTION_LIKELY_REPLACED_AD;
+
+  return NO_AD_INJECTION;
 }
 
 Action::InjectionType Action::CheckAppendChild() const {
   const base::DictionaryValue* child = NULL;
   if (!args_->GetDictionary(0u, &child))
     return NO_AD_INJECTION;
 
   return CheckDomObject(child);
 }
 
@@ skipping 55 matching lines @@
     std::string rhs_other = ActivityLogPolicy::Util::Serialize(rhs->other());
     if (lhs_other != rhs_other)
       return lhs_other < rhs_other;
   }
 
   // All fields compare as equal if this point is reached.
   return false;
 }
 
 }  // namespace extensions