Make DOMStorageContextWrapper a client of memory coordinator

content/browser/dom_storage/dom_storage_context_wrapper.cc

Index: content/browser/dom_storage/dom_storage_context_wrapper.cc
diff --git a/content/browser/dom_storage/dom_storage_context_wrapper.cc b/content/browser/dom_storage/dom_storage_context_wrapper.cc
index 52e769cf72a1e7bc86c15b670d166ca0fb39e7e0..b63e618c1018938d343cceceb4d2912c0cfa8949 100644
--- a/content/browser/dom_storage/dom_storage_context_wrapper.cc
+++ b/content/browser/dom_storage/dom_storage_context_wrapper.cc
@@ -18,6 +18,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/filesystem/public/interfaces/directory.mojom.h"
 #include "components/leveldb/public/interfaces/leveldb.mojom.h"
+#include "components/memory_coordinator/browser/memory_coordinator.h"
 #include "content/browser/dom_storage/dom_storage_area.h"
 #include "content/browser/dom_storage/dom_storage_context_impl.h"
 #include "content/browser/dom_storage/dom_storage_task_runner.h"
@@ -284,8 +285,12 @@ DOMStorageContextWrapper::DOMStorageContextWrapper(
           worker_pool->GetNamedSequenceToken("dom_storage_commit"),
           BrowserThread::GetTaskRunnerForThread(BrowserThread::IO).get()));
 
-  memory_pressure_listener_.reset(new base::MemoryPressureListener(
+  if (memory_coordinator::MemoryCoordinator::GetInstance()) {
+    memory_coordinator::MemoryCoordinator::GetInstance()->RegisterClient(this);
+  } else {
+    memory_pressure_listener_.reset(new base::MemoryPressureListener(
       base::Bind(&DOMStorageContextWrapper::OnMemoryPressure, this)));
+  }
 }
 
 DOMStorageContextWrapper::~DOMStorageContextWrapper() {}
@@ -365,6 +370,11 @@ void DOMStorageContextWrapper::Shutdown() {
       FROM_HERE,
       DOMStorageTaskRunner::PRIMARY_SEQUENCE,
       base::Bind(&DOMStorageContextImpl::Shutdown, context_));
+  if (memory_coordinator::MemoryCoordinator::GetInstance()) {
+    memory_coordinator::MemoryCoordinator::GetInstance()->UnregisterClient(
+        this);
+  }
+
 }
 
 void DOMStorageContextWrapper::Flush() {
@@ -384,10 +394,36 @@ void DOMStorageContextWrapper::OpenLocalStorage(
 
 void DOMStorageContextWrapper::OnMemoryPressure(
     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  PurgeMemory(memory_pressure_level ==
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
+}
+
+void DOMStorageContextWrapper::OnMemoryStateChange(
+    memory_coordinator::MemoryState state) {
+  // TODO(hajimehoshi): As OnMemoryStateChange changes the state, we should
+  // adjust the limitation to the amount of cache, DomStroageContextImpl doesn't
+  // have such limitation so far though.
+  switch (state) {
+  case memory_coordinator::MemoryState::NORMAL:

[michaeln, 2016/09/14 19:40:49]

style nit: indent cases by 2 spaces

[hajimehoshi, 2016/09/15 09:14:46]

Done.

+    // Don't have to purge memory here.
+    break;
+  case memory_coordinator::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.
+    PurgeMemory(false);
+    break;
+  case memory_coordinator::MemoryState::UNKNOWN:
+  case memory_coordinator::MemoryState::SUSPENDED:
+    NOTREACHED();

[michaeln, 2016/09/14 19:40:49]

maybe comment that SUSPENDED doesn't occur in the main browser process

[hajimehoshi, 2016/09/15 09:14:46]

Done.

+    break;
+  }
+}
+
+void DOMStorageContextWrapper::PurgeMemory(bool aggressively)
+{

[michaeln, 2016/09/14 19:40:49]

style nit: move { up to the end of the previous line

[hajimehoshi, 2016/09/15 09:14:46]

Done.

   DOMStorageContextImpl::PurgeOption purge_option =
       DOMStorageContextImpl::PURGE_UNOPENED;
-  if (memory_pressure_level ==
-      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
+  if (aggressively) {
     purge_option = DOMStorageContextImpl::PURGE_AGGRESSIVE;
   }
   context_->task_runner()->PostTask(