Add GPU fingerprint information to breakpad microdumps.

src/client/linux/microdump_writer/microdump_writer_unittest.cc

Index: src/client/linux/microdump_writer/microdump_writer_unittest.cc
diff --git a/src/client/linux/microdump_writer/microdump_writer_unittest.cc b/src/client/linux/microdump_writer/microdump_writer_unittest.cc
index 035e73c1aa83c98da02bdf654ec3c0fa00dfc8a4..a524647460c7ae80ab5f2ea67004606df279cb0e 100644
--- a/src/client/linux/microdump_writer/microdump_writer_unittest.cc
+++ b/src/client/linux/microdump_writer/microdump_writer_unittest.cc
@@ -54,6 +54,7 @@ void CrashAndGetMicrodump(
     const MappingList& mappings,
     const char* build_fingerprint,
     const char* product_info,
+    const char* gpu_fingerprint,
     scoped_array<char>* buf) {
   int fds[2];
   ASSERT_NE(-1, pipe(fds));
@@ -85,7 +86,7 @@ void CrashAndGetMicrodump(
   ASSERT_NE(-1, dup2(err_fd, STDERR_FILENO));
 
   ASSERT_TRUE(WriteMicrodump(child, &context, sizeof(context), mappings,
-      build_fingerprint, product_info));
+                             build_fingerprint, product_info, gpu_fingerprint));
 
   // Revert stderr back to the console.
   dup2(save_err, STDERR_FILENO);