Remove renderer notifications of memory pressure.

content/browser/memory/memory_pressure_controller_impl.cc

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "content/browser/memory/memory_pressure_controller_impl.h"
-
-#include "base/bind.h"
-#include "content/browser/memory/memory_message_filter.h"
-#include "content/public/browser/browser_thread.h"
-
-namespace content {
-
-MemoryPressureControllerImpl::MemoryPressureControllerImpl() {}
-
-MemoryPressureControllerImpl::~MemoryPressureControllerImpl() {}
-
-void MemoryPressureControllerImpl::OnMemoryMessageFilterAdded(
-    MemoryMessageFilter* filter) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  // Add the message filter to the set of all memory message filters and check
-  // that it wasn't there beforehand.
-  const bool success =
-      memory_message_filters_.insert(
-                                 std::make_pair(filter->process_host(), filter))
-          .second;
-  DCHECK(success);
-
-  // There's no need to send a message to the child process if memory pressure
-  // notifications are not suppressed.
-  if (base::MemoryPressureListener::AreNotificationsSuppressed())
-    filter->SendSetPressureNotificationsSuppressed(true);
-}
-
-void MemoryPressureControllerImpl::OnMemoryMessageFilterRemoved(
-    MemoryMessageFilter* filter) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  // Remove the message filter from the set of all memory message filters,
-  // ensuring that it was there beforehand.
-  auto it = memory_message_filters_.find(filter->process_host());
-  if (it == memory_message_filters_.end())
-    return;
-  DCHECK_EQ(filter, it->second);
-  memory_message_filters_.erase(it);
-}
-
-// static
-MemoryPressureControllerImpl* MemoryPressureControllerImpl::GetInstance() {
-  return base::Singleton<
-      MemoryPressureControllerImpl,
-      base::LeakySingletonTraits<MemoryPressureControllerImpl>>::get();
-}
-
-void
-MemoryPressureControllerImpl::SetPressureNotificationsSuppressedInAllProcesses(
-    bool suppressed) {
-  if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
-    // Note that passing base::Unretained(this) is safe here because the
-    // controller is a leaky singleton.
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(&MemoryPressureControllerImpl::
-                       SetPressureNotificationsSuppressedInAllProcesses,
-                   base::Unretained(this), suppressed));
-    return;
-  }
-
-  // Enable/disable suppressing memory notifications in the browser process.
-  base::MemoryPressureListener::SetNotificationsSuppressed(suppressed);
-
-  // Enable/disable suppressing memory notifications in all child processes.
-  for (const auto& filter_pair : memory_message_filters_)
-    filter_pair.second->SendSetPressureNotificationsSuppressed(suppressed);
-}
-
-void MemoryPressureControllerImpl::SimulatePressureNotificationInAllProcesses(
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  DCHECK_NE(level, base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
-
-  if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
-    // Note that passing base::Unretained(this) is safe here because the
-    // controller is a leaky singleton.
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(&MemoryPressureControllerImpl::
-                       SimulatePressureNotificationInAllProcesses,
-                   base::Unretained(this), level));
-    return;
-  }
-
-  // Simulate memory pressure notification in the browser process.
-  base::MemoryPressureListener::SimulatePressureNotification(level);
-
-  // Simulate memory pressure notification in all child processes.
-  for (const auto& filter_pair : memory_message_filters_)
-    filter_pair.second->SendSimulatePressureNotification(level);
-}
-
-void MemoryPressureControllerImpl::SendPressureNotification(
-    const BrowserChildProcessHost* child_process_host,
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  SendPressureNotificationImpl(child_process_host, level);
-}
-
-void MemoryPressureControllerImpl::SendPressureNotification(
-    const RenderProcessHost* render_process_host,
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  SendPressureNotificationImpl(render_process_host, level);
-}
-
-void MemoryPressureControllerImpl::SendPressureNotificationImpl(
-    const void* child_process_host,
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
-    // Note that passing base::Unretained(this) is safe here because the
-    // controller is a leaky singleton. It's also safe to pass an untyped
-    // child process pointer as the address is only used as a key for lookup in
-    // a map; at no point is it dereferenced.
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(&MemoryPressureControllerImpl::SendPressureNotificationImpl,
-                   base::Unretained(this), child_process_host, level));
-    return;
-  }
-
-  if (base::MemoryPressureListener::AreNotificationsSuppressed())
-    return;
-
-  // Find the appropriate message filter and dispatch the message.
-  auto it = memory_message_filters_.find(child_process_host);
-  if (it != memory_message_filters_.end())
-    it->second->SendPressureNotification(level);
-}
-
-}  // namespace content