Use std::string and ::string explicitly in gtest and gmock code.

This merges a Google-internal change (117235625).

Original CL description:
This CL was created manually in about an hour with sed, a Python script
to find all the places unqualified 'string' was mentioned, and some help
from Emacs to add the "std::" qualifications, plus a few manual tweaks.

googlemock/src/gmock-cardinalities.cc

@@ -92,7 +92,7 @@ class BetweenCardinalityImpl : public CardinalityInterface {
 };
 
 // Formats "n times" in a human-friendly way.
-inline internal::string FormatTimes(int n) {
+inline std::string FormatTimes(int n) {
   if (n == 1) {
     return "once";
   } else if (n == 2) {

googlemock/src/gmock-internal-utils.cc

@@ -76,7 +76,7 @@ GTEST_API_ string ConvertIdentifierNameToWords(const char* id_name) {
 class GoogleTestFailureReporter : public FailureReporterInterface {
  public:
   virtual void ReportFailure(FailureType type, const char* file, int line,
-                             const string& message) {
+                             const std::string& message) {
     AssertHelper(type == kFatal ?
                  TestPartResult::kFatalFailure :
                  TestPartResult::kNonFatalFailure,
@@ -128,8 +128,7 @@ GTEST_API_ bool LogIsVisible(LogSeverity severity) {
 // stack_frames_to_skip is treated as 0, since we don't know which
 // function calls will be inlined by the compiler and need to be
 // conservative.
-GTEST_API_ void Log(LogSeverity severity,
-                    const string& message,
+GTEST_API_ void Log(LogSeverity severity, const std::string& message,
                     int stack_frames_to_skip) {
   if (!LogIsVisible(severity))
     return;

googlemock/src/gmock-matchers.cc

@@ -379,7 +379,7 @@ void MatchMatrix::Randomize() {
   }
 }
 
-string MatchMatrix::DebugString() const {
+std::string MatchMatrix::DebugString() const {
   ::std::stringstream ss;
   const char *sep = "";
   for (size_t i = 0; i < LhsSize(); ++i) {
@@ -441,10 +441,9 @@ void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(
 // Returns false, writing an explanation to 'listener', if and only
 // if the success criteria are not met.
 bool UnorderedElementsAreMatcherImplBase::
-VerifyAllElementsAndMatchersAreMatched(
-    const ::std::vector<string>& element_printouts,
-    const MatchMatrix& matrix,
-    MatchResultListener* listener) const {
+    VerifyAllElementsAndMatchersAreMatched(
+        const ::std::vector<std::string>& element_printouts,
+        const MatchMatrix& matrix, MatchResultListener* listener) const {
   bool result = true;
   ::std::vector<char> element_matched(matrix.LhsSize(), 0);
   ::std::vector<char> matcher_matched(matrix.RhsSize(), 0);

googlemock/src/gmock-spec-builders.cc

@@ -58,16 +58,15 @@ GTEST_API_ GTEST_DEFINE_STATIC_MUTEX_(g_gmock_mutex);
 // Logs a message including file and line number information.
 GTEST_API_ void LogWithLocation(testing::internal::LogSeverity severity,
                                 const char* file, int line,
-                                const string& message) {
+                                const std::string& message) {
   ::std::ostringstream s;
   s << file << ":" << line << ": " << message << ::std::endl;
   Log(severity, s.str(), 0);
 }
 
 // Constructs an ExpectationBase object.
-ExpectationBase::ExpectationBase(const char* a_file,
-                                 int a_line,
-                                 const string& a_source_text)
+ExpectationBase::ExpectationBase(const char* a_file, int a_line,
+                                 const std::string& a_source_text)
     : file_(a_file),
       line_(a_line),
       source_text_(a_source_text),
@@ -244,7 +243,7 @@ GTEST_API_ ThreadLocal<Sequence*> g_gmock_implicit_sequence;
 
 // Reports an uninteresting call (whose description is in msg) in the
 // manner specified by 'reaction'.
-void ReportUninterestingCall(CallReaction reaction, const string& msg) {
+void ReportUninterestingCall(CallReaction reaction, const std::string& msg) {
   // Include a stack trace only if --gmock_verbose=info is specified.
   const int stack_frames_to_skip =
       GMOCK_FLAG(verbose) == kInfoVerbosity ? 3 : -1;