fix signed warning errors in unittests

src/processor/minidump_processor_unittest.cc

 // Copyright (c) 2006, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 396 matching lines @@
             google_breakpad::PROCESS_OK);
   ASSERT_EQ(state.system_info()->os, kSystemInfoOS);
   ASSERT_EQ(state.system_info()->os_short, kSystemInfoOSShort);
   ASSERT_EQ(state.system_info()->os_version, kSystemInfoOSVersion);
   ASSERT_EQ(state.system_info()->cpu, kSystemInfoCPU);
   ASSERT_EQ(state.system_info()->cpu_info, kSystemInfoCPUInfo);
   ASSERT_TRUE(state.crashed());
   ASSERT_EQ(state.crash_reason(), "EXCEPTION_ACCESS_VIOLATION_WRITE");
   ASSERT_EQ(state.crash_address(), 0x45U);
   ASSERT_EQ(state.threads()->size(), size_t(1));
-  EXPECT_EQ((*state.threads())[0]->tid(), 3060);
+  EXPECT_EQ((*state.threads())[0]->tid(), 3060U);
   ASSERT_EQ(state.requesting_thread(), 0);
   EXPECT_EQ(1171480435U, state.time_date_stamp());
   EXPECT_EQ(1171480435U, state.process_create_time());
 
   CallStack *stack = state.threads()->at(0);
   ASSERT_TRUE(stack);
   ASSERT_EQ(stack->frames()->size(), 4U);
 
   ASSERT_TRUE(stack->frames()->at(0)->module);
   ASSERT_EQ(stack->frames()->at(0)->module->base_address(), 0x400000U);
@@ skipping 208 matching lines @@
   ASSERT_EQ(1U, state.threads()->size());
   ASSERT_EQ(0U, state.threads()->at(0)->frames()->size());
 }
 
 }  // namespace
 
 int main(int argc, char *argv[]) {
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();
 }