Introduce background Download process to android

content/public/android/java/src/org/chromium/content/app/ChildProcessService.java

Index: content/public/android/java/src/org/chromium/content/app/ChildProcessService.java
diff --git a/content/public/android/java/src/org/chromium/content/app/ChildProcessService.java b/content/public/android/java/src/org/chromium/content/app/ChildProcessService.java
index 849f9c753402e4a393219a229bacde645bc97429..2d6352b4e895447e96092a452ac6691f98da62fa 100644
--- a/content/public/android/java/src/org/chromium/content/app/ChildProcessService.java
+++ b/content/public/android/java/src/org/chromium/content/app/ChildProcessService.java
@@ -51,6 +51,7 @@ import java.util.concurrent.atomic.AtomicReference;
 public class ChildProcessService extends Service {
     private static final String MAIN_THREAD_NAME = "ChildProcessMain";
     private static final String TAG = "ChildProcessService";
+    protected static final FileDescriptorInfo[] EMPTY_FILE_DESCRIPTOR_INFO = {};
     private IChildProcessCallback mCallback;
 
     // This is the native "Main" thread for the renderer / utility process.
@@ -89,6 +90,7 @@ public class ChildProcessService extends Service {
         // NOTE: Implement any IChildProcessService methods here.
         @Override
         public int setupConnection(Bundle args, IChildProcessCallback callback) {
+            assert isBoundService();
             mCallback = callback;
             getServiceInfo(args);
             return Process.myPid();
@@ -237,6 +239,7 @@ public class ChildProcessService extends Service {
 
     @Override
     public IBinder onBind(Intent intent) {
+        assert isBoundService();
         // We call stopSelf() to request that this service be stopped as soon as the client
         // unbinds. Otherwise the system may keep it around and available for a reconnect. The
         // child processes do not currently support reconnect; they must be initialized from
@@ -289,10 +292,7 @@ public class ChildProcessService extends Service {
                 mFdInfos = new FileDescriptorInfo[fdInfosAsParcelable.length];
                 System.arraycopy(fdInfosAsParcelable, 0, mFdInfos, 0, fdInfosAsParcelable.length);
             } else {
-                // TODO(qinmin): On earlier androird versions, a started service running in another
-                // process can get killed after Chrome is killed. To work around this issue, client
-                // will never bind to the service. As a result, the file descriptors needs to be
-                // passed through an intent when starting the service.
+                mFdInfos = getFileDescriptorInfo(bundle);

[svaldez, 2016/01/25 15:33:43]

Move to DownloadServiceProcess, so that ChildServiceProcess doesn't need to
worry about 'getFileDescriptorInfo' and 'isBoundService'?

Also is it correct to ignore the new descriptors from getFileDescriptorInfo if
we have some passed as part of the parcel?

[qinmin, 2016/01/25 22:48:23]

Let the DownloadServiceProcess override getServiceInfo() function? Then there
are lot of duplicated code. see my comments in DownloadProcessService.

If we passed the FDs from the parcel, then getFileDescriptorInfo() should not
get called. For bound service, they can pass FDs inside the parcel, but for a
started service, we cannot do that.

             }
             Bundle sharedRelros = bundle.getBundle(Linker.EXTRA_LINKER_SHARED_RELROS);
             if (sharedRelros != null) {
@@ -412,6 +412,23 @@ public class ChildProcessService extends Service {
     }
 
     /**
+     * Retrive an array of FileDescriptorInfo from a bundle.
+     * @param bundle The bundle through the intent to launch the service.
+     * @return an array of FileDescriptorInfo.
+     */
+    protected FileDescriptorInfo[] getFileDescriptorInfo(Bundle bundle) {
+        return EMPTY_FILE_DESCRIPTOR_INFO;
+    }
+
+    /**
+     * Check whether the service is a bound service or a started service.
+     * @return true if the service is bound, or false otherwise.
+     */
+    protected boolean isBoundService() {
+        return true;
+    }
+
+    /**
      * Helper for registering FileDescriptorInfo objects with GlobalFileDescriptors.
      * This includes the IPC channel, the crash dump signals and resource related
      * files.