StrictMode: now in more system server threads.

Who knew there were so many Loopers in the system server?

This adds dropbox logging for the activity manager thread, policy
thread, and window manager thread.

The goal's to catch more stuttering.

Change-Id: I999a6ff4a955f0ef549b12a38796b843ade5fe66

core/java/android/app/ContextImpl.java

@@ -1182,6 +1182,13 @@ class ContextImpl extends Context {
     /* package */ static DropBoxManager createDropBoxManager() {
         IBinder b = ServiceManager.getService(DROPBOX_SERVICE);
         IDropBoxManagerService service = IDropBoxManagerService.Stub.asInterface(b);
+        if (service == null) {
+            // Don't return a DropBoxManager that will NPE upon use.
+            // This also avoids caching a broken DropBoxManager in
+            // getDropBoxManager during early boot, before the
+            // DROPBOX_SERVICE is registered.
+            return null;
+        }
         return new DropBoxManager(service);
     }
 

services/java/com/android/server/WindowManagerService.java

@@ -86,6 +86,7 @@ import android.os.PowerManager;
 import android.os.Process;
 import android.os.RemoteException;
 import android.os.ServiceManager;
+import android.os.StrictMode;
 import android.os.SystemClock;
 import android.os.SystemProperties;
 import android.os.TokenWatcher;
@@ -944,6 +945,11 @@ public class WindowManagerService extends IWindowManager.Stub
                 notifyAll();
             }
 
+            // For debug builds, log event loop stalls to dropbox for analysis.
+            if (StrictMode.conditionallyEnableDebugLogging()) {
+                Slog.i(TAG, "Enabled StrictMode logging for WMThread's Looper");
+            }
+
             Looper.loop();
         }
     }
@@ -981,6 +987,11 @@ public class WindowManagerService extends IWindowManager.Stub
                 notifyAll();
             }
 
+            // For debug builds, log event loop stalls to dropbox for analysis.
+            if (StrictMode.conditionallyEnableDebugLogging()) {
+                Slog.i(TAG, "Enabled StrictMode for PolicyThread's Looper");
+            }
+
             Looper.loop();
         }
     }

services/java/com/android/server/am/ActivityManagerService.java

@@ -1349,6 +1349,11 @@ public final class ActivityManagerService extends ActivityManagerNative
                 }
             }
 
+            // For debug builds, log event loop stalls to dropbox for analysis.
+            if (StrictMode.conditionallyEnableDebugLogging()) {
+                Slog.i(TAG, "Enabled StrictMode logging for AThread's Looper");
+            }
+
             Looper.loop();
         }
     }