Allow compiling the google-breakpad code using a global ::string class instead of std::string.

For more details take a look at common/using_std_string.h

BUG=

Change-Id: Ifebfc57f691ef3a3bef8cfed7106c567985edffc
Reviewed-on: https://chromium-review.googlesource.com/399738
Reviewed-by: Mark Mentovai <mark@chromium.org>

src/google_breakpad/processor/proc_maps_linux.h

@@ -52,7 +52,7 @@ struct MappedMemoryRegion {
 
 // Parses /proc/<pid>/maps input data and stores in |regions|. Returns true
 // and updates |regions| if and only if all of |input| was successfully parsed.
-bool ParseProcMaps(const std::string& input,
+bool ParseProcMaps(const string& input,
                    std::vector<MappedMemoryRegion>* regions);
 
 }  // namespace google_breakpad