AU: Changes for deltas on traditional bios machines.

BUG=None
TEST=Attached unittests/tested on image

- Fix uninitialized variable err in action processor unittest

- Let Omaha dictate if an update is a delta or full update

- Bug fix in delta generator for differently-sized images

- More logging when applying delta updates

- Fix infinite loop in http fetcher unittest

- log each HTTP connection to know when a dropped connection is
  reestablished.

- Detect when speed goes below a threshold and reestablish HTTP
  connection (currently < 10bytes/sec for 90 contiguous seconds).

- Fix stack overflow in libcurl http fetcher.

- optimize out a lot of needless CPU usage in libcurl http fetcher
  (turns out adding a glib main loop source uses a lot of CPU).

- subprocess: pass PATH, log stdout/stderr

- postinstall runner: support for ext3 and ext4 target filesystems.

Review URL: http://codereview.chromium.org/2805027
diff --git a/action_processor_unittest.cc b/action_processor_unittest.cc
index 0657207..40275a0 100644
--- a/action_processor_unittest.cc
+++ b/action_processor_unittest.cc
@@ -61,7 +61,11 @@
 class MyActionProcessorDelegate : public ActionProcessorDelegate {
  public:
   explicit MyActionProcessorDelegate(const ActionProcessor* processor)
-      : processor_(processor), processing_done_called_(false) {}
+      : processor_(processor),
+        processing_done_called_(false),
+        processing_stopped_called_(false),
+        action_completed_called_(false),
+        action_completed_success_(false) {}
 
   virtual void ProcessingDone(const ActionProcessor* processor, bool success) {
     EXPECT_EQ(processor_, processor);