[Chromoting] Use device::PowerSaveBlocker to block screen saver

remoting/host/chromoting_host_context.h

Index: remoting/host/chromoting_host_context.h
diff --git a/remoting/host/chromoting_host_context.h b/remoting/host/chromoting_host_context.h
index 351c1307922fb5f72742b729048ad435c36344dd..46f3d06cf7212c810bdc9b9f035e556fb8d5a2b1 100644
--- a/remoting/host/chromoting_host_context.h
+++ b/remoting/host/chromoting_host_context.h
@@ -27,13 +27,18 @@ class AutoThreadTaskRunner;
 // process.  This class is virtual only for testing purposes (see below).
 class ChromotingHostContext {
  public:
-  // Create threads and URLRequestContextGetter for use by a host.
+  // Creates threads and URLRequestContextGetter for use by a host.
   // During shutdown the caller should tear-down the ChromotingHostContext and
   // then continue to run until |ui_task_runner| is no longer referenced.
   // nullptr is returned if any threads fail to start.
   static std::unique_ptr<ChromotingHostContext> Create(
       scoped_refptr<AutoThreadTaskRunner> ui_task_runner);
 
+  // Creates a ChromotingHostContext instance, which uses the input task runner
+  // for all jobs. This is for tests only.
+  static std::unique_ptr<ChromotingHostContext> CreateForTest(
+      scoped_refptr<AutoThreadTaskRunner> task_runner);
+
 #if defined(OS_CHROMEOS)
   // Attaches task runners to the relevant browser threads for the chromoting
   // host.  Must be called on the UI thread of the browser process.
@@ -53,7 +58,7 @@ class ChromotingHostContext {
 
   ~ChromotingHostContext();
 
-  std::unique_ptr<ChromotingHostContext> Copy();
+  std::unique_ptr<ChromotingHostContext> Copy() const;
 
   // Task runner for the thread that is used for the UI.
   scoped_refptr<AutoThreadTaskRunner> ui_task_runner() const;
@@ -88,6 +93,17 @@ class ChromotingHostContext {
       const;
 
  private:
+  // Creates a ChromotingHostContext instance. Returns nullptr if any of the
+  // input task runner is nullptr.
+  static std::unique_ptr<ChromotingHostContext> Create(
+      scoped_refptr<AutoThreadTaskRunner> ui_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> audio_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> file_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> input_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> network_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> video_capture_task_runner,
+      scoped_refptr<AutoThreadTaskRunner> video_encode_task_runner);
+
   ChromotingHostContext(
       scoped_refptr<AutoThreadTaskRunner> ui_task_runner,
       scoped_refptr<AutoThreadTaskRunner> audio_task_runner,