memory coordinator: Purge memory under memory pressure

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 637cc8be392f955524b04f83f44d73bb1c9eeea3..2f67ce3f77cfd78015a6b498fc67274f5e66283c 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -2234,7 +2234,26 @@ void RenderThreadImpl::OnMemoryStateChange(base::MemoryState state) {
   }
 }
 
+void RenderThreadImpl::RecordPurgeMemory(RendererMemoryMetrics before) {

[kinuko, 2017/03/28 08:07:00]

nit: please move this after OnPurgeMemory() (to match the method order in .cc
and in .h)

[bashi, 2017/03/28 09:37:17]

Done.

+  RendererMemoryMetrics after;
+  GetRendererMemoryMetrics(&after);
+  int64_t mbytes = static_cast<int64_t>(before.total_allocated_mb) -
+                   static_cast<int64_t>(after.total_allocated_mb);
+  if (mbytes < 0)
+    mbytes = 0;
+  UMA_HISTOGRAM_MEMORY_LARGE_MB("Memory.Experimental.Renderer.PurgedMemory",
+                                mbytes);
+}
+
 void RenderThreadImpl::OnPurgeMemory() {
+  RendererMemoryMetrics metrics;
+  GetRendererMemoryMetrics(&metrics);
+  GetRendererScheduler()->DefaultTaskRunner()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&RenderThreadImpl::RecordPurgeMemory, base::Unretained(this),
+                 std::move(metrics)),
+      base::TimeDelta::FromSeconds(2));

[kinuko, 2017/03/28 08:07:00]

nit: Would be nice to have a short note about why 2 sec.

[bashi, 2017/03/28 09:37:17]

Done.

+
   OnTrimMemoryImmediately();
   ReleaseFreeMemory();
   ClearMemory();