Add SpdyString alias for std::string in net/spdy.

net/spdy/fuzzing/hpack_fuzz_util_test.cc

Index: net/spdy/fuzzing/hpack_fuzz_util_test.cc
diff --git a/net/spdy/fuzzing/hpack_fuzz_util_test.cc b/net/spdy/fuzzing/hpack_fuzz_util_test.cc
index d5f0677963727a72dd0fd3776df8dcdedc047b75..bbc72dfdbb07c44604f877bbe772b371d5168cb6 100644
--- a/net/spdy/fuzzing/hpack_fuzz_util_test.cc
+++ b/net/spdy/fuzzing/hpack_fuzz_util_test.cc
@@ -18,7 +18,6 @@ namespace net {
 namespace test {
 
 using std::map;
-using std::string;
 using test::a2b_hex;
 
 TEST(HpackFuzzUtilTest, GeneratorContextInitialization) {
@@ -85,15 +84,16 @@ TEST(HpackFuzzUtilTest, ParsesSequenceOfHeaderBlocks) {
 }
 
 TEST(HpackFuzzUtilTest, SerializedHeaderBlockPrefixes) {
-  EXPECT_EQ(string("\x00\x00\x00\x00", 4), HpackFuzzUtil::HeaderBlockPrefix(0));
-  EXPECT_EQ(string("\x00\x00\x00\x05", 4), HpackFuzzUtil::HeaderBlockPrefix(5));
+  EXPECT_EQ(SpdyString("\x00\x00\x00\x00", 4),
+            HpackFuzzUtil::HeaderBlockPrefix(0));
+  EXPECT_EQ(SpdyString("\x00\x00\x00\x05", 4),
+            HpackFuzzUtil::HeaderBlockPrefix(5));
   EXPECT_EQ("\x4f\xb3\x0a\x91", HpackFuzzUtil::HeaderBlockPrefix(1337133713));
 }
 
 TEST(HpackFuzzUtilTest, PassValidInputThroughAllStages) {
   // Example lifted from HpackDecoderTest.SectionD4RequestHuffmanExamples.
-  string input = a2b_hex("828684418cf1e3c2e5f23a6ba0ab90f4"
-                         "ff");
+  SpdyString input = a2b_hex("828684418cf1e3c2e5f23a6ba0ab90f4ff");
 
   HpackFuzzUtil::FuzzerContext context;
   HpackFuzzUtil::InitializeFuzzerContext(&context);
@@ -135,7 +135,7 @@ TEST(HpackFuzzUtilTest, ValidFuzzExamplesRegressionTest) {
 
 TEST(HpackFuzzUtilTest, FlipBitsMutatesBuffer) {
   char buffer[] = "testbuffer1234567890";
-  string unmodified(buffer, arraysize(buffer) - 1);
+  SpdyString unmodified(buffer, arraysize(buffer) - 1);
 
   EXPECT_EQ(unmodified, buffer);
   HpackFuzzUtil::FlipBits(reinterpret_cast<uint8_t*>(buffer),