video_capture_manager: filter out unexpected app state changes on Android

content/browser/renderer_host/media/video_capture_manager.cc

 // Copyright (c) 2012 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/renderer_host/media/video_capture_manager.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 234 matching lines @@
 
 void VideoCaptureManager::Register(
     MediaStreamProviderListener* listener,
     const scoped_refptr<base::SingleThreadTaskRunner>& device_task_runner) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(!listener_);
   DCHECK(!device_task_runner_.get());
   listener_ = listener;
   device_task_runner_ = device_task_runner;
 #if defined(OS_ANDROID)
+  has_stopped_activities = false;
   app_status_listener_.reset(new base::android::ApplicationStatusListener(
       base::Bind(&VideoCaptureManager::OnApplicationStateChange,
                  base::Unretained(this))));
 #endif
 }
 
 void VideoCaptureManager::Unregister() {
   DCHECK(listener_);
   listener_ = nullptr;
 }
@@ skipping 809 matching lines @@
       base::Bind(&VideoCaptureManager::OnDeviceLayerInitialized, this,
                  and_then));
 }
 #endif
 
 #if defined(OS_ANDROID)
 void VideoCaptureManager::OnApplicationStateChange(
     base::android::ApplicationState state) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  if (state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
+  // Only release/resume devices when the Application state changes from
+  // RUNNING->STOPPED->RUNNING.
+  if (state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES &&
+      has_stopped_activities) {

[perkj_chrome, 2016/06/28 08:59:26]

Suggest rename |has_stopped_activities| to
|application_state_has_running_activities_|  and change the check accordingly. 

     ResumeDevices();
+    has_stopped_activities = false;
   } else if (state == base::android::APPLICATION_STATE_HAS_STOPPED_ACTIVITIES) {
     ReleaseDevices();
+    has_stopped_activities = true;
   }
 }
 
 void VideoCaptureManager::ReleaseDevices() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   for (auto& entry : devices_) {
     // Do not stop Content Video Capture devices, e.g. Tab or Screen capture.
     if (entry->stream_type != MEDIA_DEVICE_VIDEO_CAPTURE)
       continue;
 
     DoStopDevice(entry);
   }
 }
 
 void VideoCaptureManager::ResumeDevices() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   for (auto& entry : devices_) {
     // Do not resume Content Video Capture devices, e.g. Tab or Screen capture.
-    // Do not try to restart already running devices. A device will be running
-    // if the Application state changes from
-    // APPLICATION_STATE_HAS_RUNNING_ACTIVITIES
-    // ->APPLICATION_STATE_HAS_PAUSED_ACTIVITIES
-    // ->APPLICATION_STATE_HAS_RUNNING_ACTIVITIES
+    // Do not try to restart already running devices.
     if (entry->stream_type != MEDIA_DEVICE_VIDEO_CAPTURE ||
         entry->video_capture_device())
       continue;
 
     // Check if the device is already in the start queue.
     bool device_in_queue = false;
     for (auto& request : device_start_queue_) {
       if (request.serial_id() == entry->serial_id) {
         device_in_queue = true;
         break;
       }
     }
 
     if (!device_in_queue) {
       // Session ID is only valid for Screen capture. So we can fake it to
       // resume video capture devices here.
       QueueStartDevice(kFakeSessionId, entry, entry->parameters);
     }
   }
 }
 #endif  // defined(OS_ANDROID)
 
 }  // namespace content