Introduce background Download process to android

content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java

Index: content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java
index d4eb121258264ad0c581635fab11a271afc1355f..3f8d3e73a4e1adef330469a04f7ddbc6791c7d4c 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConstants.java
@@ -19,4 +19,18 @@ public class ChildProcessConstants {
     // Used to pass the CPU features mask to child processes.
     public static final String EXTRA_CPU_FEATURES =
             "com.google.android.apps.chrome.extra.cpu_features";
+
+    // An unique ID for DownloadProcessService to post a foreground notifications, 1797 is the year
+    // the element chromium was discovered.
+    public static final int DOWNLOAD_PROCESS_NOTIFICATION_ID = 1797;

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

I believe the right way of using IDs is to add it to the resource file and then
reference that:
chrome/android/java/res/values/ids.xml

That way we don't end up accidentally having overlapping IDs.

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

If you check ids.xml, the ids are mostly for UI. The problem is that different
builds(content_shell, chrome, chrome_public) uses different xmls, so for a
single Id, we need to add it to different xmls, which makes is even harder to
maintain.

+    // Used to pass the IChildProcessCallback to a child process. For a started service,
+    // file descriptors cannot be passed in the intent that starts the service. As a result,
+    // a Binder object needs to be passed through which the child process can retrieve the file
+    // descriptors.
+    public static final String EXTRA_CHILD_PROCESS_CALLBACK =
+            "com.google.android.apps.chrome.extra.child_process_callback";
+    // Used to pass the channel ID to the download process.
+    public static final String EXTRA_CHANNEL_ID = "com.google.android.apps.chrome.extra.channel_id";
+    // kProcessChannelID switch defined in ipc_switches.h.
+    public static final String PROCESS_CHANNEL_ID_SWITCH = "channel";
 }