Support storing information about what modules are loaded in the process.

base/debug/activity_tracker.h

Index: base/debug/activity_tracker.h
diff --git a/base/debug/activity_tracker.h b/base/debug/activity_tracker.h
index 20d35473ddd15cb2981e2659824aef405f86aeb9..fa0143bafdd8388c1fdb031dd7319894d8dc5609 100644
--- a/base/debug/activity_tracker.h
+++ b/base/debug/activity_tracker.h
@@ -632,6 +632,7 @@ class BASE_EXPORT GlobalActivityTracker {
   enum : uint32_t {
     kTypeIdActivityTracker = 0x5D7381AF + 3,   // SHA1(ActivityTracker) v3
     kTypeIdUserDataRecord = 0x615EDDD7 + 2,    // SHA1(UserDataRecord) v2
+    kTypeIdModulesRecord = 0x484E2E03 + 1,     // SHA1(ModulesRecord) v1
     kTypeIdGlobalLogMessage = 0x4CF434F9 + 1,  // SHA1(GlobalLogMessage) v1
     kTypeIdGlobalDataRecord = kTypeIdUserDataRecord + 1000,
 
@@ -639,6 +640,17 @@ class BASE_EXPORT GlobalActivityTracker {
     kTypeIdUserDataRecordFree = ~kTypeIdUserDataRecord,
   };
 
+  struct ModuleInfo {
+    bool is_loaded = false;
+    uintptr_t address = 0;
+    size_t size = 0;
+    std::string file;
+    std::string version;
+    std::string identifier;
+    std::string debug_file;
+    std::string debug_identifier;
+  };
+
   // This is a thin wrapper around the thread-tracker's ScopedActivity that
   // accesses the global tracker to provide some of the information, notably
   // which thread-tracker to use. It is safe to create even if activity
@@ -742,6 +754,10 @@ class BASE_EXPORT GlobalActivityTracker {
   // only store critical messages such as FATAL ones.
   void RecordLogMessage(StringPiece message);
 
+  // Records a module load/unload event. This is safe to call multiple times
+  // even with the same information.
+  void RecordModuleInfo(const ModuleInfo& info);
+
   // Accesses the global data record for storing arbitrary key/value pairs.
   ActivityUserData& user_data() { return user_data_; }
 
@@ -818,6 +834,10 @@ class BASE_EXPORT GlobalActivityTracker {
   // be written from the main UI thread.
   ActivityUserData user_data_;
 
+  // A map of global module information, keyed by module path.
+  std::map<const std::string, PersistentMemoryAllocator::Reference> modules_;

[manzagop (departed), 2016/12/14 20:08:54]

I believe it's possible to have the same module loaded at multiple offsets. We
might need the key to be something like pair<base_address, string>.

[bcwhite, 2016/12/14 21:59:05]

That would be annoying.  How about we wait to see if it's a real problem before
addressing it?

[manzagop (departed), 2016/12/16 16:09:31]

Totally. :( IIRC Siggi said this is to be expected so minimally put a comment to
highlight this case. Shouldn't affect chrome modules though.

[bcwhite, 2016/12/16 18:35:15]

Done.  If it comes to it, I'll probably support multiple addresses in the
ModuleInfoRecord.

+  base::Lock modules_lock_;
+
   // The active global activity tracker.
   static GlobalActivityTracker* g_tracker_;