Fix permissions lint errors.

- Add ACCESS_NETWORK_STATE to core library. It seems fairly fundamental. We should
  also be using it elsewhere (e.g. to fail fast if there's no network).
- Add annotation to force apps using PlatformScheduler to declare RECEIVE_BOOT_PERMISSION

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=194763051

demos/main/src/main/AndroidManifest.xml

@@ -19,7 +19,6 @@
 
   <uses-permission android:name="android.permission.INTERNET"/>
   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
-  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
   <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
 
   <uses-feature android:name="android.software.leanback" android:required="false"/>

library/core/src/main/AndroidManifest.xml

@@ -14,4 +14,7 @@
      limitations under the License.
 -->
 
-<manifest package="com.google.android.exoplayer2.core"/>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.google.android.exoplayer2.core">
+  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+</manifest>

library/core/src/main/java/com/google/android/exoplayer2/scheduler/PlatformScheduler.java

@@ -26,6 +26,7 @@ import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.os.PersistableBundle;
+import android.support.annotation.RequiresPermission;
 import android.util.Log;
 import com.google.android.exoplayer2.util.Util;
 
@@ -78,6 +79,7 @@ public final class PlatformScheduler implements Scheduler {
    * @param serviceAction The action which the service will be started with.
    * @param servicePackage The package of the service which contains the logic of the job.
    */
+  @RequiresPermission(android.Manifest.permission.RECEIVE_BOOT_COMPLETED)
   public PlatformScheduler(
       Context context,
       Requirements requirements,
@@ -103,6 +105,8 @@ public final class PlatformScheduler implements Scheduler {
     return true;
   }
 
+  // @RequiresPermission constructor annotation should ensure the permission is present.
+  @SuppressWarnings("MissingPermission")
   private static JobInfo buildJobInfo(
       Context context,
       Requirements requirements,

library/core/src/main/java/com/google/android/exoplayer2/scheduler/Requirements.java

@@ -32,8 +32,6 @@ import java.lang.annotation.RetentionPolicy;
 
 /**
  * Defines a set of device state requirements.
- *
- * <p>To use network type requirement, application needs to have ACCESS_NETWORK_STATE permission.
  */
 public final class Requirements {