[Downloads] Introduce GUIDs for downloads.

components/history/core/browser/history_database.cc

Index: components/history/core/browser/history_database.cc
diff --git a/components/history/core/browser/history_database.cc b/components/history/core/browser/history_database.cc
index 94608254400394bb882d9ecedf13d48de1850933..c9a94f885bdf621e1e3d18b1c344bb11ffb19407 100644
--- a/components/history/core/browser/history_database.cc
+++ b/components/history/core/browser/history_database.cc
@@ -36,7 +36,7 @@ namespace {
 // Current version number. We write databases at the "current" version number,
 // but any previous version that can read the "compatible" one can make do with
 // our database without *too* many bad effects.
-const int kCurrentVersionNumber = 29;
+const int kCurrentVersionNumber = 30;
 const int kCompatibleVersionNumber = 16;
 const char kEarlyExpirationThresholdKey[] = "early_expiration_threshold";
 const int kMaxHostsInMemory = 10000;
@@ -490,6 +490,15 @@ sql::InitStatus HistoryDatabase::EnsureCurrentVersion() {
     meta_table_.SetVersionNumber(cur_version);
   }
 
+  if (cur_version == 29) {
+    if (!MigrateHashHttpMethodAndGenerateGuids()) {
+      LOG(WARNING) << "Unable to migrate history to version 30";
+      return sql::INIT_FAILURE;
+    }
+    cur_version++;
+    meta_table_.SetVersionNumber(cur_version);
+  }
+
   // When the version is too old, we just try to continue anyway, there should
   // not be a released product that makes a database too old for us to handle.
   LOG_IF(WARNING, cur_version < GetCurrentVersion()) <<