[tracing] Add SkResourceCache statistics to chrome://tracing (chrome side)

skia/ext/SkTraceMemoryDump_chrome.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "skia/ext/SkTraceMemoryDump_chrome.h"
+
+#include "base/trace_event/memory_allocator_dump.h"
+#include "base/trace_event/memory_dump_manager.h"
+#include "base/trace_event/process_memory_dump.h"
+#include "skia/ext/SkDiscardableMemory_chrome.h"
+
+namespace skia {
+
+SkTraceMemoryDump_Chrome::SkTraceMemoryDump_Chrome(
+    base::trace_event::ProcessMemoryDump* process_memory_dump)
+    : process_memory_dump_(process_memory_dump) {}
+
+SkTraceMemoryDump_Chrome::~SkTraceMemoryDump_Chrome() {}
+
+void SkTraceMemoryDump_Chrome::dumpNumericValue(const char* dumpName,
+                                                const char* valueName,
+                                                const char* units,
+                                                uint64_t value) {
+  auto mad = process_memory_dump_->GetAllocatorDump(dumpName);
+  if (!mad)
+    mad = process_memory_dump_->CreateAllocatorDump(dumpName);
+  mad->AddScalar(valueName, units, value);
+}
+
+void SkTraceMemoryDump_Chrome::setMemoryBacking(const char* dumpName,
+                                                const char* backingType,
+                                                const char* backingObjectId) {
+  if (strcmp(backingType, "malloc") == 0) {
+    auto mad = process_memory_dump_->GetAllocatorDump(dumpName);
+    if (!mad)
+      mad = process_memory_dump_->CreateAllocatorDump(dumpName);

[Primiano Tucci (use gerrit), 2015/08/26 15:34:01]

do you need the GetOrCreate semantic also here? if so you could extract a
GetOrCreateAllocatorDump method

[ssid, 2015/08/26 15:45:19]

Ah, sorry. I just updated the CL. after i sent for review.

+    process_memory_dump_->AddSuballocation(
+        mad->guid(), base::trace_event::MemoryDumpManager::GetInstance()
+                         ->system_allocator_pool_name());
+  }
+}
+
+void SkTraceMemoryDump_Chrome::setDiscardableMemoryBacking(
+    const char* dumpName,
+    const SkDiscardableMemory& discardableMemoryObject) {
+  DCHECK(!process_memory_dump_->GetAllocatorDump(dumpName));
+  const SkDiscardableMemoryChrome& memory =

[Primiano Tucci (use gerrit), 2015/08/26 15:34:01]

why this dcheck. don't you want the GetOrCreate semantic here? Why hard failing
if you already have a dump (which was intended to be the original plan)?

[ssid, 2015/08/26 15:45:19]

Hm, hard failing here because it will fail inside the discardable manager which
creates dump. Instead of failing at a random place, failing here is better to
debug. This is what I was discussing with you offline.

+      static_cast<const SkDiscardableMemoryChrome&>(discardableMemoryObject);
+  auto mad = memory.CreateMemoryAllocatorDump(dumpName, process_memory_dump_);
+  DCHECK(mad);

[Primiano Tucci (use gerrit), 2015/08/26 15:34:01]

please s/memory/discardable_memory_obj/ or similar

[ssid, 2015/08/26 15:45:19]

Done.

+}
+
+}  // namespace skia