clang/win: Let some chromium_code targets build with -Wextra.

base/message_loop/message_loop_unittest.cc

Index: base/message_loop/message_loop_unittest.cc
diff --git a/base/message_loop/message_loop_unittest.cc b/base/message_loop/message_loop_unittest.cc
index dcac66245be13dcf5746ce9c5629942192eecd06..c08dc7f9a98f32ab853becc20baa3d2df2751b42 100644
--- a/base/message_loop/message_loop_unittest.cc
+++ b/base/message_loop/message_loop_unittest.cc
@@ -336,7 +336,7 @@ void RunTest_RecursiveDenial2(MessageLoop::Type message_loop_type) {
   WaitForSingleObject(event.Get(), INFINITE);
   MessageLoop::current()->Run();
 
-  ASSERT_EQ(order.Size(), 17);
+  ASSERT_EQ(17u, order.Size());
   EXPECT_EQ(order.Get(0), TaskItem(RECURSIVE, 1, true));
   EXPECT_EQ(order.Get(1), TaskItem(RECURSIVE, 1, false));
   EXPECT_EQ(order.Get(2), TaskItem(MESSAGEBOX, 2, true));
@@ -380,7 +380,7 @@ void RunTest_RecursiveSupport2(MessageLoop::Type message_loop_type) {
   WaitForSingleObject(event.Get(), INFINITE);
   MessageLoop::current()->Run();
 
-  ASSERT_EQ(order.Size(), 18);
+  ASSERT_EQ(18u, order.Size());
   EXPECT_EQ(order.Get(0), TaskItem(RECURSIVE, 1, true));
   EXPECT_EQ(order.Get(1), TaskItem(RECURSIVE, 1, false));
   EXPECT_EQ(order.Get(2), TaskItem(MESSAGEBOX, 2, true));
@@ -522,7 +522,7 @@ void TestIOHandler::Init() {
 
   DWORD read;
   EXPECT_FALSE(ReadFile(file_.Get(), buffer_, size(), &read, context()));
-  EXPECT_EQ(ERROR_IO_PENDING, GetLastError());
+  EXPECT_EQ(static_cast<DWORD>(ERROR_IO_PENDING), GetLastError());
   if (wait_)
     WaitForIO();
 }
@@ -615,8 +615,9 @@ void RunTest_WaitForIO() {
   DWORD written;
   EXPECT_TRUE(WriteFile(server1.Get(), buffer, sizeof(buffer), &written, NULL));
   PlatformThread::Sleep(2 * delay);
-  EXPECT_EQ(WAIT_TIMEOUT, WaitForSingleObject(callback1_called.Get(), 0)) <<
-      "handler1 has not been called";
+  EXPECT_EQ(static_cast<DWORD>(WAIT_TIMEOUT),
+            WaitForSingleObject(callback1_called.Get(), 0))
+      << "handler1 has not been called";
 
   EXPECT_TRUE(WriteFile(server2.Get(), buffer, sizeof(buffer), &written, NULL));