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 62f983b5e87024f2334691db3db543ebfd2d6683..a558d70a391cc7a75551aa782b4550d2d92b04c4 100644
--- a/base/debug/activity_tracker.h
+++ b/base/debug/activity_tracker.h
@@ -646,6 +646,25 @@ class BASE_EXPORT GlobalActivityTracker {
     kTypeIdUserDataRecordFree = ~kTypeIdUserDataRecord,
   };
 
+  struct BASE_EXPORT ModuleInfo {
+    ModuleInfo();
+    ModuleInfo(ModuleInfo&& rhs);
+    ModuleInfo(const ModuleInfo& rhs);
+    ~ModuleInfo();
+
+    ModuleInfo& operator=(ModuleInfo&& rhs);
+    ModuleInfo& operator=(const ModuleInfo& rhs);
+
+    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
@@ -749,10 +768,15 @@ 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_; }
 
  private:
+  friend class GlobalActivityAnalyzer;
   friend class ScopedThreadActivity;
   friend class ActivityTrackerTest;
 
@@ -764,6 +788,47 @@ class BASE_EXPORT GlobalActivityTracker {
     kCachedUserDataMemories = 10,
   };
 
+  // State of a module as stored in persistent memory. This supports a single
+  // loading of a module only. If modules are loaded multiple times at
+  // different addresses, only the last will be recorded and an unload will
+  // not revert to the information of any other addresses.
+  struct BASE_EXPORT ModuleInfoRecord {
+    // SHA1(ModuleInfoRecord): Increment this if structure changes!
+    static constexpr uint32_t kPersistentTypeId = 0x05DB5F41 + 1;
+
+    // Expected size for 32/64-bit check by PersistentMemoryAllocator.
+    static constexpr size_t kExpectedInstanceSize = 24;
+
+    // The atomic unfortunately makes this a "complex" class on some compilers
+    // and thus requires an out-of-line constructor & destructor even though
+    // they do nothing.
+    ModuleInfoRecord();
+    ~ModuleInfoRecord();
+
+    uint64_t address;               // The base address of the module.
+    uint64_t size;                  // The size of the module in bytes.
+    std::atomic<uint32_t> changes;  // Number load/unload actions.
+    uint16_t pickle_size;           // The size of the following pickle.
+    uint8_t loaded;                 // Flag if module is loaded or not.
+    char pickle[1];                 // Other strings; may allocate larger.
+
+    // Decodes/encodes storage structure from more generic info structure.
+    bool DecodeTo(GlobalActivityTracker::ModuleInfo* info,
+                  size_t record_size) const;
+    bool EncodeFrom(const GlobalActivityTracker::ModuleInfo& info,
+                    size_t record_size);
+
+    // Updates the core information without changing the encoded strings. This
+    // is useful when a known module changes state (i.e. new load or unload).
+    bool UpdateFrom(const GlobalActivityTracker::ModuleInfo& info);
+
+    // Determines the required memory size for the encoded storage.
+    static size_t EncodedSize(const GlobalActivityTracker::ModuleInfo& info);
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ModuleInfoRecord);
+  };
+
   // A thin wrapper around the main thread-tracker that keeps additional
   // information that the global tracker needs to handle joined threads.
   class ManagedActivityTracker : public ThreadActivityTracker {
@@ -825,6 +890,10 @@ 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, ModuleInfoRecord*> modules_;
+  base::Lock modules_lock_;
+
   // The active global activity tracker.
   static GlobalActivityTracker* g_tracker_;