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 fc83bd7fb946a937142e210324832a6e540a82d2..6a4641f6ace3b003492dd01c04e98586515ce429 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -2230,7 +2230,26 @@ void RenderThreadImpl::OnMemoryStateChange(base::MemoryState state) {
   }
 }
 
+void RenderThreadImpl::RecordPurgeMemory(RendererMemoryMetrics before) {
+  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)

[haraken, 2017/03/24 11:55:39]

Maybe we want to count this case in some way too? e.g., treating as mbytes == 0.

[bashi, 2017/03/28 03:15:31]

Done.

+    return;
+  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));

[haraken, 2017/03/24 11:55:39]

I guess tasak@ was using 15 seconds or something. I'm not sure what the right
number would be :)

[bashi, 2017/03/28 03:15:31]

I think 2 seconds is enough and 15 sec seems too long for my case as the process
may be foregrounded.

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