blink/bindings: Report the original size of ParkableStrings.

The original size is the size without compression. This allows to see the
savings in memory-infra memory dumps.

Also add a trace event for the aging task.

Bug: 924164
Change-Id: I5cb2f968f8ec51d330b66fa211fde048bb5e2323
Reviewed-on: https://chromium-review.googlesource.com/c/1456657
Commit-Queue: Benoit L <lizeb@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629926}

third_party/blink/renderer/platform/bindings/parkable_string_manager.cc

@@ -12,6 +12,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/trace_event/memory_allocator_dump.h"
 #include "base/trace_event/process_memory_dump.h"
+#include "base/trace_event/trace_event.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/renderer/platform/bindings/parkable_string.h"
 #include "third_party/blink/renderer/platform/memory_pressure_listener.h"
@@ -133,12 +134,14 @@ bool ParkableStringManager::OnMemoryDump(
   base::trace_event::MemoryAllocatorDump* dump =
       pmd->CreateAllocatorDump("parkable_strings");
 
+  size_t original_size = 0;
   size_t uncompressed_size = 0;
   size_t compressed_size = 0;
   size_t metadata_size = 0;
   size_t overhead_size = 0;
 
   for (ParkableStringImpl* str : unparked_strings_.Values()) {
+    original_size += str->CharactersSizeInBytes();
     uncompressed_size += str->CharactersSizeInBytes();
     metadata_size += sizeof(ParkableStringImpl);
 
@@ -147,6 +150,7 @@ bool ParkableStringManager::OnMemoryDump(
   }
 
   for (ParkableStringImpl* str : parked_strings_) {
+    original_size += str->CharactersSizeInBytes();
     compressed_size += str->compressed_size();
     metadata_size += sizeof(ParkableStringImpl);
   }
@@ -154,6 +158,7 @@ bool ParkableStringManager::OnMemoryDump(
   size_t total_size =
       uncompressed_size + compressed_size + metadata_size + overhead_size;
   dump->AddScalar("size", "bytes", total_size);
+  dump->AddScalar("original_size", "bytes", original_size);
   dump->AddScalar("uncompressed_size", "bytes", uncompressed_size);
   dump->AddScalar("compressed_size", "bytes", compressed_size);
   dump->AddScalar("metadata_size", "bytes", metadata_size);
@@ -320,6 +325,7 @@ void ParkableStringManager::AgeStringsAndPark() {
   if (!base::FeatureList::IsEnabled(kCompressParkableStringsInForeground))
     return;
 
+  TRACE_EVENT0("blink", "ParkableStringManager::AgeStringsAndPark");
   has_pending_aging_task_ = false;
 
   WTF::Vector<ParkableStringImpl*> unparked =

third_party/blink/renderer/platform/bindings/parkable_string_test.cc

@@ -688,6 +688,10 @@ TEST_F(ParkableStringTest, ReportMemoryDump) {
       pmd.GetAllocatorDump("parkable_strings");
   ASSERT_NE(nullptr, dump);
 
+  MemoryAllocatorDump::Entry original("original_size", "bytes",
+                                      2 * kSizeKb * 1000);
+  EXPECT_THAT(dump->entries(), Contains(Eq(ByRef(original))));
+
   // |parkable1| is unparked.
   MemoryAllocatorDump::Entry uncompressed("uncompressed_size", "bytes",
                                           kSizeKb * 1000);