Pepper: Log in UMA when an interface is used.

ppapi/proxy/interface_list_unittest.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 "base/hash.h"
 #include "ppapi/c/ppb_core.h"
 #include "ppapi/proxy/interface_list.h"
 #include "ppapi/proxy/ppapi_proxy_test.h"
 
 namespace ppapi {
 namespace proxy {
 
 class InterfaceListTest : public PluginProxyTest {
  public:
   // Wrapper function so we can use the private InterfaceList::AddPPB.
@@ skipping 40 matching lines @@
   ASSERT_TRUE(list.GetInterfaceForPPB(dev_channel_iface_name) == NULL);
   ASSERT_TRUE(list.GetInterfaceForPPB(dev_iface_name) == dev_iface_addr);
 
   InterfaceList::SetProcessGlobalPermissions(
       PpapiPermissions(PERMISSION_DEV | PERMISSION_DEV_CHANNEL));
   ASSERT_TRUE(list.GetInterfaceForPPB(dev_channel_iface_name) ==
               dev_channel_iface_addr);
   ASSERT_TRUE(list.GetInterfaceForPPB(dev_iface_name) == dev_iface_addr);
 }
 
+// Test that the hash function provided by base::Hash is unchanged. This is so
+// that we will generate correct values when logging interface use to UMA.
+TEST_F(InterfaceListTest, InterfaceHash) {
+  std::string name = "PPB_InputEvent;1.0";
+  uint32 data = base::Hash(name.c_str(), name.size());
+  int hash = static_cast<int>(data & 0x7fffffff);

[Alexei Svitkine (slow), 2014/02/04 18:53:31]

Can you make a function in InterfaceList to compute the hash (including the
masking) and call it from this test, rather than duplicating the logic here?
That way, the two won't be able to diverge.

+  EXPECT_EQ(612625164, hash);
+
+  name = "PPB_TCPSocket;1.1";
+  data = base::Hash(name.c_str(), name.size());
+  hash = static_cast<int>(data & 0x7fffffff);
+  EXPECT_EQ(79708274, hash);
+}
+
 }  // namespace proxy
 }  // namespace ppapi