Switch the Linux minidump writer to use MDCVInfoELF for CV data.

src/client/linux/microdump_writer/microdump_writer.cc

Index: src/client/linux/microdump_writer/microdump_writer.cc
diff --git a/src/client/linux/microdump_writer/microdump_writer.cc b/src/client/linux/microdump_writer/microdump_writer.cc
index 91697ed840f930635c494764cac29ca6dd55b09a..2cbeb4f315483af9166ef2602b01e6d7f704460c 100644
--- a/src/client/linux/microdump_writer/microdump_writer.cc
+++ b/src/client/linux/microdump_writer/microdump_writer.cc
@@ -32,6 +32,7 @@
 
 #include "client/linux/microdump_writer/microdump_writer.h"
 
+#include <algorithm>
 #include <sys/utsname.h>
 
 #include "client/linux/dump_writer_common/thread_info.h"
@@ -40,11 +41,13 @@
 #include "client/linux/handler/microdump_extra_info.h"
 #include "client/linux/log/log.h"
 #include "client/linux/minidump_writer/linux_ptrace_dumper.h"
+#include "common/linux/file_id.h"
 #include "common/linux/linux_libc_support.h"
 
 namespace {
 
 using google_breakpad::ExceptionHandler;
+using google_breakpad::kDefaultBuildIdSize;
 using google_breakpad::LinuxDumper;
 using google_breakpad::LinuxPtraceDumper;
 using google_breakpad::MappingInfo;
@@ -53,6 +56,7 @@ using google_breakpad::MicrodumpExtraInfo;
 using google_breakpad::RawContextCPU;
 using google_breakpad::ThreadInfo;
 using google_breakpad::UContextReader;
+using google_breakpad::wasteful_vector;
 
 const size_t kLineBufferSize = 2048;
 
@@ -336,18 +340,25 @@ class MicrodumpWriter {
                   bool member,
                   unsigned int mapping_id,
                   const uint8_t* identifier) {
-    MDGUID module_identifier;
+    wasteful_vector<uint8_t> identifier_bytes(dumper_->allocator(),
+                                              kDefaultBuildIdSize);
     if (identifier) {
       // GUID was provided by caller.
-      my_memcpy(&module_identifier, identifier, sizeof(MDGUID));
+      identifier_bytes.resize(sizeof(MDGUID));
+      my_memcpy(&identifier_bytes[0], identifier, sizeof(MDGUID));
     } else {
       dumper_->ElfFileIdentifierForMapping(
           mapping,
           member,
           mapping_id,
-          reinterpret_cast<uint8_t*>(&module_identifier));
+          identifier_bytes);
     }
 
+    // Copy as many bytes of |identifier| as will fit into a MDGUID
+    MDGUID module_identifier = {0};
+    memcpy(&module_identifier, &identifier_bytes[0],
+           std::min(sizeof(MDGUID), identifier_bytes.size()));
+
     char file_name[NAME_MAX];
     char file_path[NAME_MAX];
     dumper_->GetMappingEffectiveNameAndPath(