Introduce a delay before a high priority binding is unbound (reland).

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

Index: content/public/android/java/src/org/chromium/content/browser/ChildProcessConnection.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnection.java b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnection.java
index ddd88797d18c027697cde5851d846fac6c310676..424ad90a6ba569781ff40d03be70a4cf198ee3ef 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnection.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnection.java
@@ -268,7 +268,6 @@ public class ChildProcessConnection {
             mInitialBinding.unbind();
             mStrongBinding.unbind();
             mWaivedBinding.unbind();
-            mAttachAsActiveCount = 0;
             if (mService != null) {
                 mService = null;
                 mPID = 0;
@@ -355,14 +354,22 @@ public class ChildProcessConnection {
         TraceEvent.end();
     }
 
+    private static final long REMOVE_INITIAL_BINDING_DELAY_MILLIS = 1 * 1000;  // One second.
+
     /**
      * Called to remove the strong binding estabilished when the connection was started. It is safe
-     * to call this multiple times.
+     * to call this multiple times. The binding is removed after a fixed delay period so that the
+     * renderer will not be killed immediately after the call.
      */
     void removeInitialBinding() {
-        synchronized(mUiThreadLock) {
-            mInitialBinding.unbind();
-        }
+        ThreadUtils.postOnUiThreadDelayed(new Runnable() {

[klobag.chromium, 2013/07/19 16:19:55]

why need this?

[klobag.chromium, 2013/07/19 18:19:05]

Just saw the comment in the other CL, thanks.

This can be called a lot even it only needs to be called once. Can we avoid spam
the message queue? 

[ppi, 2013/07/22 13:50:38]

Done.

+            @Override
+            public void run() {
+                synchronized(mUiThreadLock) {
+                    mInitialBinding.unbind();
+                }
+            }
+        }, REMOVE_INITIAL_BINDING_DELAY_MILLIS);
     }
 
     /**
@@ -384,21 +391,29 @@ public class ChildProcessConnection {
         }
     }
 
+    private static final long DETACH_AS_ACTIVE_DELAY_MILLIS = 5 * 1000;  // Five seconds.
+
     /**
-     * Called when the service is no longer considered active.
+     * Called when the service is no longer considered active. Actual binding is removed after a
+     * fixed delay period so that the renderer will not be killed immediately after the call.
      */
     void detachAsActive() {
-        synchronized(mUiThreadLock) {
-            assert mAttachAsActiveCount > 0;
-            if (mService == null) {
-                Log.w(TAG, "The connection is not bound for " + mPID);
-                return;
-            }
-            mAttachAsActiveCount--;
-            if (mAttachAsActiveCount == 0) {
-                mStrongBinding.unbind();
+        ThreadUtils.postOnUiThreadDelayed(new Runnable() {
+            @Override
+            public void run() {
+                synchronized(mUiThreadLock) {
+                    assert mAttachAsActiveCount > 0;
+                    if (mService == null) {

[klobag.chromium, 2013/07/19 16:19:55]

If you move line 405 to above 410, you can leave stop() unchanged. Otherwise can
you add a comment in stop() to explain why we don't reset the count?

[ppi, 2013/07/22 13:50:38]

Thanks, done (moved).

+                        Log.w(TAG, "The connection is not bound for " + mPID);
+                        return;
+                    }
+                    mAttachAsActiveCount--;
+                    if (mAttachAsActiveCount == 0) {
+                        mStrongBinding.unbind();
+                    }
+                }
             }
-        }
+        }, DETACH_AS_ACTIVE_DELAY_MILLIS);
     }