[remoting android] Explicitly add 'exported' attribute in the manifest.

remoting/android/java/AndroidManifest.xml.jinja2

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
         package="{{ APK_PACKAGE_NAME }}">
     <uses-sdk android:minSdkVersion="14"
             android:targetSdkVersion="23"/>
     <uses-permission android:name="android.permission.GET_ACCOUNTS"/>
     <uses-permission android:name="android.permission.INTERNET"/>
 
     <application android:label="@string/product_name_android"
             android:name="org.chromium.chromoting.RemotingApplication"
             android:icon="@mipmap/logo_remote_desktop_launcher"
             android:theme="@style/BaseTheme"
             android:allowBackup="false">
         <meta-data
                 android:name="com.google.android.gms.version"
                 android:value="@integer/google_play_services_version"/>
-        <activity android:name="org.chromium.chromoting.Chromoting"
-                android:configChanges="orientation|screenSize"
-                android:theme="@style/BaseTheme.NavigationDrawer"
-                android:launchMode="singleTask">
+        <activity
+            android:name="org.chromium.chromoting.Chromoting"
+            android:configChanges="orientation|screenSize"
+            android:exported="true"
+            android:theme="@style/BaseTheme.NavigationDrawer"
+            android:launchMode="singleTask">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
         <activity
             android:name="org.chromium.chromoting.ThirdPartyTokenFetcher$OAuthRedirectActivity"
             android:enabled="false"
+            android:exported="true"
             android:noHistory="true">
             <!-- TODO(kevinp): suppress once crbug.com/501593 is fixed. -->
             <!--suppress AppIndexingError -->
             <intent-filter>
                 <action android:name="android.intent.action.VIEW"/>
                 <category android:name="android.intent.category.DEFAULT"/>
                 <category android:name="android.intent.category.BROWSABLE"/>
                 <data android:scheme="{{ APK_PACKAGE_NAME }}"/>
                 <data android:path="/oauthredirect/"/>
             </intent-filter>
         </activity>
-        <activity android:name="org.chromium.chromoting.Desktop"
-                android:windowSoftInputMode="adjustResize"/>
-        <activity android:name="org.chromium.chromoting.help.HelpActivity"
-                android:configChanges="orientation|screenSize"
-                android:uiOptions="splitActionBarWhenNarrow">
-        </activity>
-        <activity android:name="org.chromium.chromoting.help.CreditsActivity"/>
+        <activity
+            android:name="org.chromium.chromoting.Desktop"
+            android:exported="false"
+            android:windowSoftInputMode="adjustResize"/>
+        <activity
+            android:name="org.chromium.chromoting.help.HelpActivity"
+            android:configChanges="orientation|screenSize"
+            android:exported="false"
+            android:uiOptions="splitActionBarWhenNarrow"/>
+        <activity
+            android:name="org.chromium.chromoting.help.CreditsActivity"
+            android:exported="false"/>
     </application>
 </manifest>