Add analyzer support for multiple processes.

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 922528fb38702fdd023eeec906bba6fb8d7cb22c..05a034f0eb8d53a92e24309846779279f664bb24 100644
--- a/base/debug/activity_tracker.h
+++ b/base/debug/activity_tracker.h
@@ -377,7 +377,7 @@ class BASE_EXPORT ActivityUserData {
    private:
     friend class ActivityUserData;
 
-    ValueType type_;
+    ValueType type_ = END_OF_VALUES;
     uint64_t short_value_;    // Used to hold copy of numbers, etc.
     std::string long_value_;  // Used to hold copy of raw/string data.
     StringPiece ref_value_;   // Used to hold reference to external data.
@@ -440,9 +440,9 @@ class BASE_EXPORT ActivityUserData {
 
   // Creates a snapshot of the key/value pairs contained within. The returned
   // data will be fixed, independent of whatever changes afterward. There is
-  // protection against concurrent modification of the values but no protection
-  // against a complete overwrite of the contents; the caller must ensure that
-  // the memory segment is not going to be re-initialized while this runs.
+  // some protection against concurrent modification. This will return false
+  // if the data is invalid or if a complete overwrite of the contents is
+  // detected.
   bool CreateSnapshot(Snapshot* output_snapshot) const;
 
   // Gets the base memory address used for storing data.
@@ -531,6 +531,12 @@ class BASE_EXPORT ActivityUserData {
   // A pointer to the memory header for this instance.
   MemoryHeader* const header_;
 
+  // These hold values used when initially creating the object. They are
+  // compared against current header values to check for outside changes.
+  const uint32_t orig_data_id;
+  const int64_t orig_process_id;
+  const int64_t orig_create_stamp;
+
   DISALLOW_COPY_AND_ASSIGN(ActivityUserData);
 };
 
@@ -565,6 +571,9 @@ class BASE_EXPORT ThreadActivityTracker {
     // truncated due to internal length limitations.
     std::string thread_name;
 
+    // The timestamp at which this process was created.
+    int64_t create_stamp;
+
     // The process and thread IDs. These values have no meaning other than
     // they uniquely identify a running process and a running thread within
     // that process.  Thread-IDs can be re-used across different processes