Implement screen capture for android

chrome/browser/media/media_capture_devices_dispatcher.cc

Index: chrome/browser/media/media_capture_devices_dispatcher.cc
diff --git a/chrome/browser/media/media_capture_devices_dispatcher.cc b/chrome/browser/media/media_capture_devices_dispatcher.cc
index 79c93f5c1124def7b7aa119c90259682a0ae0532..bd7f12e38c22ffa310a2ef16a1f8e5352e4649d3 100644
--- a/chrome/browser/media/media_capture_devices_dispatcher.cc
+++ b/chrome/browser/media/media_capture_devices_dispatcher.cc
@@ -584,6 +584,12 @@ void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
       user_approved = (result == chrome::MESSAGE_BOX_RESULT_YES);
     }
 
+#if defined(OS_ANDROID)
+    // For android, MediaProjectionManager API will start an activity to
+    // prompt the user whether to allow screen capture. So here user_approved
+    // is useless.
+    user_approved = true;
+#endif
     if (user_approved || component_extension || whitelisted_extension) {
       content::DesktopMediaID screen_id;
 #if defined(OS_CHROMEOS)