Correctly hash the input of MatchModuleWhitelistString() in pver4.

Also add a test.

BUG=673827

Review-Url: https://codereview.chromium.org/2577963004
Cr-Commit-Position: refs/heads/master@{#438951}

components/safe_browsing_db/v4_local_database_manager.cc

@@ -17,6 +17,7 @@
 #include "components/safe_browsing_db/v4_feature_list.h"
 #include "components/safe_browsing_db/v4_protocol_manager_util.h"
 #include "content/public/browser/browser_thread.h"
+#include "crypto/sha2.h"
 
 using content::BrowserThread;
 using base::TimeTicks;
@@ -312,8 +313,10 @@ bool V4LocalDatabaseManager::MatchModuleWhitelistString(
     return true;
   }
 
+  // str is the module's filename.  Convert to hash.
+  FullHash hash = crypto::SHA256HashString(str);
   return HandleHashSynchronously(
-      str, StoresToCheck({GetChromeFilenameClientIncidentId()}));
+      hash, StoresToCheck({GetChromeFilenameClientIncidentId()}));
 }
 
 ThreatSource V4LocalDatabaseManager::GetThreatSource() const {

components/safe_browsing_db/v4_local_database_manager_unittest.cc

@@ -11,6 +11,7 @@
 #include "components/safe_browsing_db/v4_local_database_manager.h"
 #include "components/safe_browsing_db/v4_test_util.h"
 #include "content/public/test/test_browser_thread_bundle.h"
+#include "crypto/sha2.h"
 #include "net/url_request/test_url_fetcher_factory.h"
 #include "testing/platform_test.h"
 
@@ -407,4 +408,27 @@ TEST_F(V4LocalDatabaseManagerTest, TestMatchMalwareIP) {
       v4_local_database_manager_));
 }
 
+TEST_F(V4LocalDatabaseManagerTest, TestMatchModuleWhitelist) {
+  StopLocalDatabaseManager();
+  v4_local_database_manager_ =
+      make_scoped_refptr(new FakeV4LocalDatabaseManager(base_dir_.GetPath()));
+  SetTaskRunnerForTest();
+  StartLocalDatabaseManager();
+  WaitForTasksOnTaskRunner();
+
+  StoreAndHashPrefixes store_and_hash_prefixes;
+  store_and_hash_prefixes.emplace_back(GetChromeFilenameClientIncidentId(),
+                                       crypto::SHA256HashString("chrome.dll"));
+
+  ReplaceV4Database(store_and_hash_prefixes);
+
+  // No match -- i.e. not whitelisted
+  EXPECT_FALSE(
+      v4_local_database_manager_->MatchModuleWhitelistString("badstuff.dll"));
+
+  // Whitelisted.
+  EXPECT_TRUE(
+      v4_local_database_manager_->MatchModuleWhitelistString("chrome.dll"));
+}
+
 }  // namespace safe_browsing