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/omaha_request_action_unittest.cc b/omaha_request_action_unittest.cc
old mode 100644
new mode 100755
index cd91f68..cc37d7a
--- a/omaha_request_action_unittest.cc
+++ b/omaha_request_action_unittest.cc
@@ -46,6 +46,7 @@
                 "appid=\"") + app_id + "\" status=\"ok\"><ping "
       "status=\"ok\"/><updatecheck DisplayVersion=\"" + display_version + "\" "
       "MoreInfo=\"" + more_info_url + "\" Prompt=\"" + prompt + "\" "
+      "IsDelta=\"true\" "
       "codebase=\"" + codebase + "\" "
       "hash=\"" + hash + "\" needsadmin=\"" + needsadmin + "\" "
       "size=\"" + size + "\" status=\"ok\"/></app></gupdate>";
@@ -229,6 +230,7 @@
   EXPECT_EQ("1.2.3.4", response.display_version);
   EXPECT_EQ("http://code/base", response.codebase);
   EXPECT_EQ("http://more/info", response.more_info_url);
+  EXPECT_TRUE(response.is_delta);
   EXPECT_EQ("HASH1234=", response.hash);
   EXPECT_EQ(123, response.size);
   EXPECT_FALSE(response.needs_admin);
@@ -398,6 +400,7 @@
   EXPECT_EQ("1.2.3.4", response.display_version);
   EXPECT_EQ("http://code/base", response.codebase);
   EXPECT_EQ("", response.more_info_url);
+  EXPECT_FALSE(response.is_delta);
   EXPECT_EQ("HASH1234=", response.hash);
   EXPECT_EQ(123, response.size);
   EXPECT_TRUE(response.needs_admin);