Wake Lock API implementation (Chromium part)

content/browser/wake_lock/wake_lock_service_context.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/wake_lock/wake_lock_service_context.h"
+
+#include "base/bind.h"
+#include "content/browser/power_save_blocker_impl.h"
+#include "content/browser/web_contents/web_contents_impl.h"
+#include "content/browser/web_contents/web_contents_view.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/power_save_blocker.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/common/service_registry.h"
+
+namespace content {
+
+WakeLockServiceContext::WakeLockServiceContext(WebContents* web_contents)
+    : WebContentsObserver(web_contents),
+      weak_factory_(this) {
+}
+
+WakeLockServiceContext::~WakeLockServiceContext() {
+}
+
+void WakeLockServiceContext::RenderFrameCreated(
+    RenderFrameHost* render_frame_host) {
+  if (auto registry = render_frame_host->GetServiceRegistry()) {
+    registry->AddService<WakeLockService>(
+        base::Bind(&WakeLockServiceImpl::CreateService,
+                   weak_factory_.GetWeakPtr(),
+                   base::Unretained(render_frame_host)));
+  }
+}
+
+void WakeLockServiceContext::RenderFrameDeleted(
+    RenderFrameHost* render_frame_host) {
+  wake_lock_state_.RemoveFrame(render_frame_host);
+  UpdateBlocker();
+}
+
+void WakeLockServiceContext::RenderFrameHostChanged(
+    RenderFrameHost* old_host,
+    RenderFrameHost* new_host) {
+  wake_lock_state_.RemoveFrame(old_host);
+  UpdateBlocker();
+}
+
+void WakeLockServiceContext::RequestWakeLock(
+    RenderFrameHost* render_frame_host) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  wake_lock_state_.AddFrame(render_frame_host);
+  UpdateBlocker();
+}
+
+void WakeLockServiceContext::CancelWakeLock(
+    RenderFrameHost* render_frame_host) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  wake_lock_state_.RemoveFrame(render_frame_host);
+  UpdateBlocker();
+}
+
+void WakeLockServiceContext::CreateBlocker() {
+  DCHECK(!blocker_);
+  blocker_ = PowerSaveBlocker::Create(
+      PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep,
+      PowerSaveBlocker::kReasonOther,
+      "WakeLock API");
+  // On Android, additionaly associate the blocker with this WebContents'
+  // NativeView.
+#if defined(OS_ANDROID)
+  DCHECK(web_contents());
+  static_cast<PowerSaveBlockerImpl*>(blocker_.get())->InitDisplaySleepBlocker(
+      web_contents());
+#endif
+}
+
+void WakeLockServiceContext::RemoveBlocker() {
+  blocker_.reset();
+}
+
+void WakeLockServiceContext::UpdateBlocker() {
+  if (wake_lock_state_.HasFrame()) {
+    if (!blocker_) {
+      CreateBlocker();
+    }
+  } else {
+    RemoveBlocker();
+  }
+  NotifyUpdate();
+}
+
+void WakeLockServiceContext::NotifyUpdate() {
+  FOR_EACH_OBSERVER(Observer, observer_list_, OnUpdate());

[mlamouri (slow - plz ping), 2015/08/21 10:03:35]

Why is that needed?

+}
+
+}  // namespace content