Record call site history in LeakDetectorImpl

components/metrics/leak_detector/leak_detector_impl.h

Index: components/metrics/leak_detector/leak_detector_impl.h
diff --git a/components/metrics/leak_detector/leak_detector_impl.h b/components/metrics/leak_detector/leak_detector_impl.h
index 7c3ec24a54b7519eb8266b7efc0b06e027d3f38a..144582d704ace30acc30483fc687e3a83dade6fa 100644
--- a/components/metrics/leak_detector/leak_detector_impl.h
+++ b/components/metrics/leak_detector/leak_detector_impl.h
@@ -38,6 +38,22 @@ class LeakDetectorImpl {
   // Leak report generated by LeakDetectorImpl.
   class LeakReport {
    public:
+    // Stores a record of the allocation bookkeeping taken at a single moment in
+    // time.
+    struct AllocationBreakdown {
+      AllocationBreakdown();
+      ~AllocationBreakdown();
+
+      // The contents of |LeakDetectorImpl::size_breakdown_history_| when this
+      // report was generated. See comment description of that variable.
+      InternalVector<uint32_t> counts_by_size;
+
+      // The net number of allocations with alloc size of
+      // |Leakreport::alloc_size_bytes_| allocated from |call_stack_|, at the
+      // time this record was generated.
+      uint32_t count_for_call_stack;
+    };
+
     LeakReport();
     ~LeakReport();
 
@@ -45,9 +61,8 @@ class LeakDetectorImpl {
 
     const InternalVector<uintptr_t>& call_stack() const { return call_stack_; }
 
-    const InternalVector<InternalVector<uint32_t>>& size_breakdown_history()
-        const {
-      return size_breakdown_history_;
+    const InternalVector<AllocationBreakdown>& alloc_breakdown_history() const {
+      return alloc_breakdown_history_;
     }
 
     // Used to compare the contents of two leak reports.
@@ -65,9 +80,9 @@ class LeakDetectorImpl {
     // will contain offsets in the executable binary.
     InternalVector<uintptr_t> call_stack_;
 
-    // A snapshot of LeakDetectorImpl::size_breakdown_history_ when this report
-    // was generated. See comment description of that variable.
-    InternalVector<InternalVector<uint32_t>> size_breakdown_history_;
+    // Records of allocation bookkeeping over time. The first element is the
+    // oldest entry and the last element is the newest.
+    InternalVector<AllocationBreakdown> alloc_breakdown_history_;
   };
 
   LeakDetectorImpl(uintptr_t mapping_addr,
@@ -100,6 +115,16 @@ class LeakDetectorImpl {
     // A stack table, if this size is being profiled for stack as well.
     CallStackTable* stack_table;
 
+    // Historical records of allocation breakdown by call site, for a particular
+    // allocation size. Each entry in the list is a RankedSet containing the top
+    // call sites ordered by most number of call sites, collected during a leak
+    // analysis. The oldest record is at the head and the newest record is at
+    // the tail.
+    InternalList<RankedSet> call_site_breakdown_history;
+
+    AllocSizeEntry();
+    ~AllocSizeEntry();
+
     // Returns net number of allocs.
     uint32_t GetNetAllocs() const { return num_allocs - num_frees; }
   };
@@ -129,6 +154,22 @@ class LeakDetectorImpl {
   // current binary, just return |ptr| as an integer.
   uintptr_t GetOffset(const void* ptr) const;
 
+  // Record some of the current allocation bookkeeping. The net number of allocs
+  // per size is recorded in |size_breakdown_history_|. The net number of allocs
+  // per call site for each size is recorded in
+  // |AllocSizeEntry::call_site_breakdown_history|.
+  //
+  // Not all the net alloc counts are recorded. And the number of historical
+  // records kept is capped. If adding a new record exceeds that limit, the
+  // oldest record is discarded. See the function definition for more details.
+  void RecordCurrentAllocationDataInHistory();
+
+  // Store the data collected by RecordCurrentAllocationDataInHistory() in
+  // |*report|. Not all net alloc counts per call site will be stored, only the
+  // count for size=|size| and made from |call_site|.
+  void StoreHistoricalDataInReport(size_t size, const CallStack* call_site,
+                                   LeakReport* report);
+
   // Owns all unique call stack objects, which are allocated on the heap. Any
   // other class or function that references a call stack must get it from here,
   // but may not take ownership of the call stack object.