Make HttpNetworkSession a client of memory coordinator

net/http/http_network_session.cc

Index: net/http/http_network_session.cc
diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc
index 66a4eab8b06649bcdb76d4f5142b6912c2fe0bdc..928534cb8dbcd163c12a74cd242ba1447fb08927 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -10,6 +10,7 @@
 #include "base/compiler_specific.h"
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
+#include "base/memory/memory_coordinator_client_registry.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ -236,11 +237,13 @@ HttpNetworkSession::HttpNetworkSession(const Params& params)
 
   memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
       &HttpNetworkSession::OnMemoryPressure, base::Unretained(this))));
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 }
 
 HttpNetworkSession::~HttpNetworkSession() {
   base::STLDeleteElements(&response_drainers_);
   spdy_session_pool_.CloseAllSessions();
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Unregister(this);
 }
 
 void HttpNetworkSession::AddResponseDrainer(HttpResponseBodyDrainer* drainer) {
@@ -404,4 +407,25 @@ void HttpNetworkSession::OnMemoryPressure(
   }
 }
 
+void HttpNetworkSession::OnMemoryStateChange(base::MemoryState state) {
+  // TODO(hajimehoshi): As OnMemoryStateChange changes the state, we should
+  // adjust the limitation to the amount of cache, HttpNetworkSession doesn't
+  // have such limitation so far though.

[Ryan Sleevi, 2016/09/26 15:15:59]

I often link to
https://groups.google.com/a/chromium.org/d/topic/chromium-dev/NH-S6KCkr2M/dis...
for comments like this

// TODO(hajimehoshi): When the state changes, adjust the sizes of the caches to
reduce the limits. HttpNetworkSession doesn't have the ability to limit at
present.

(Assuming I understood the comment properly)

[hajimehoshi, 2016/09/27 11:39:29]

Done.

[hajimehoshi, 2016/09/27 11:39:29]

Done.

+  switch (state) {
+    case base::MemoryState::NORMAL:
+      break;
+    case base::MemoryState::THROTTLED:
+      // TOOD(hajimehoshi): We don't have throttling 'level' so far. When we
+      // have such value, let's change the argument accroding to the value.

[Ryan Sleevi, 2016/09/26 15:15:59]

Typo: according

But I'm also uncertain what this comment is trying to say. Is it trying to
document how //components/memory_coordinator is implemented? If so, it feels
like a layering violation - nothing will update this comment appropriately.

If there is a broader discussion of what to do when throttled, perhaps filing a
bug to attach to and explain sufficient context about what is going on makes
more sense than the comment here.

[hajimehoshi, 2016/09/27 11:39:29]

Done (removed). IIRC we don't have any plan to add this yet.

+      CloseIdleConnections();
+      break;
+    case base::MemoryState::SUSPENDED:
+    // Note that SUSPENDED never occurs in the main browser process so far.

[Ryan Sleevi, 2016/09/26 15:15:59]

//net shouldn't talk about things like "main browser process" - that's a
layering violation (//net is used in more than Chrome, but also shouldn't know
about how //chrome or //components are implemented)

case base::MemoryState::SUSPENDED:
  // Note: Not supported at present. Fall through.
case base::MemoryState::UNKNOWN:
  NOTREACHED();
  break;

[hajimehoshi, 2016/09/27 11:39:29]

Done.

+    // Fall through.
+    case base::MemoryState::UNKNOWN:
+      NOTREACHED();
+      break;
+  }
+}
+
 }  // namespace net