Record the memory pressure level in tracing

Also add this to the slow report to get a better understanding of the
pressure level when looking at a report.

Change-Id: I73bc8804cb06f5c481b7f8bdc14c79bbcdd28d2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025951Reviewed-by: oysteine <oysteine@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Auto-Submit: Sébastien Marchand <sebmarchand@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736419}

chrome/browser/sessions/tab_loader.cc

@@ -354,7 +354,8 @@ void TabLoader::OnStopTracking(WebContents* web_contents,
 void TabLoader::OnMemoryPressure(
     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
   ReentrancyHelper lifetime_helper(this);
-  TRACE_EVENT0("browser", "TabLoader::OnMemoryPressure");
+  TRACE_EVENT1("browser", "TabLoader::OnMemoryPressure", "Level",
+               memory_pressure_level);
 
   switch (memory_pressure_level) {
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:

content/renderer/render_thread_impl.cc

@@ -1990,14 +1990,16 @@ void RenderThreadImpl::PurgePluginListCache(bool reload_pages) {
 
 void RenderThreadImpl::OnMemoryPressure(
     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
-  TRACE_EVENT0("memory", "RenderThreadImpl::OnMemoryPressure");
+  TRACE_EVENT1("memory", "RenderThreadImpl::OnMemoryPressure", "Level",
+               memory_pressure_level);
   if (blink_platform_impl_) {
     blink::WebMemoryPressureListener::OnMemoryPressure(
         static_cast<blink::WebMemoryPressureLevel>(memory_pressure_level));
   }
   if (memory_pressure_level ==
-      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL)
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
     ReleaseFreeMemory();
+  }
 }
 
 void RenderThreadImpl::RecordPurgeMemory(RendererMemoryMetrics before) {

services/tracing/public/cpp/trace_event_args_whitelist.cc

@@ -42,6 +42,7 @@ const char* const kTopLevelIpcRunTaskAllowedArgs[] = {"ipc_hash", nullptr};
 const char* const kLifecyclesTaskPostedAllowedArgs[] = {
     "task_queue_name", "time_since_disabled_ms", "ipc_hash", "location",
     nullptr};
+const char* const kMemoryPressureEventsAllowedArgs[] = {"Level", nullptr};
 
 const WhitelistEntry kEventArgsWhitelist[] = {
     {"__metadata", "thread_name", nullptr},
@@ -55,7 +56,11 @@ const WhitelistEntry kEventArgsWhitelist[] = {
     {"base", "ScopedMayLoadLibraryAtBackgroundPriority",
      kScopedBlockingCallAllowedArgs},
     {"benchmark", "TestWhitelist*", nullptr},
+    {"blink", "MemoryPressureListenerRegistry::onMemoryPressure",
+     kMemoryPressureEventsAllowedArgs},
     {"browser", "KeyedServiceFactory::GetServiceForContext", nullptr},
+    {"browser", "TabLoader::OnMemoryPressure",
+     kMemoryPressureEventsAllowedArgs},
     {"fonts", "CachedFontLinkSettings::GetLinkedFonts", nullptr},
     {"fonts", "QueryLinkedFontsFromRegistry", nullptr},
     {"fonts", "RenderTextHarfBuzz::ItemizeTextToRuns::Runs", nullptr},
@@ -63,6 +68,8 @@ const WhitelistEntry kEventArgsWhitelist[] = {
     {"ipc", "GpuChannelHost::Send", nullptr},
     {"ipc", "SyncChannel::Send", nullptr},
     {"latencyInfo", "*", kInputLatencyAllowedArgs},
+    {"memory", "RenderThreadImpl::OnMemoryPressure",
+     kMemoryPressureEventsAllowedArgs},
     {"renderer_host", "*", kRendererHostAllowedArgs},
     {"shutdown", "*", nullptr},
     {"startup", "PrefProvider::PrefProvider", nullptr},

third_party/blink/renderer/platform/instrumentation/memory_pressure_listener.cc

@@ -7,6 +7,7 @@
 #include "base/allocator/partition_allocator/memory_reclaimer.h"
 #include "base/feature_list.h"
 #include "base/system/sys_info.h"
+#include "base/trace_event/common/trace_event_common.h"
 #include "build/build_config.h"
 #include "third_party/blink/public/common/device_memory/approximated_device_memory.h"
 #include "third_party/blink/public/common/features.h"
@@ -100,7 +101,8 @@ void MemoryPressureListenerRegistry::UnregisterClient(
 
 void MemoryPressureListenerRegistry::OnMemoryPressure(
     WebMemoryPressureLevel level) {
-  TRACE_EVENT0("blink", "MemoryPressureListenerRegistry::onMemoryPressure");
+  TRACE_EVENT1("blink", "MemoryPressureListenerRegistry::onMemoryPressure",
+               "Level", level);
   CHECK(IsMainThread());
   for (auto& client : clients_)
     client->OnMemoryPressure(level);