Coverage and unbundling changes for runtest.

Stop using 'adb sync' in runtest. It was unreliable even when working
with full platform builds, and doesn't work at all for unbundled apps.
Instead, use output from build command to find produced artifacts and
use 'adb install' where possible.
However, note that this approach won't sync previously built artifacts
to device.

Also adjust to build system support for code coverage. Its no longer
required to build libcore to get code coverage.

Change-Id: I9c5d37897c9570d2d29db3ec82f5c53e60a8f485

testrunner/adb_interface.py

@@ -131,6 +131,17 @@ class AdbInterface:
       logger.Log("ADB Pull Failed: Source file %s does not exist." % src)
       return False
 
+  def Install(self, apk_path):
+    """Installs apk on device.
+
+    Args:
+      apk_path: file path to apk file on host
+
+    Returns:
+      output of install command
+    """
+    return self.SendCommand("install -r %s" % apk_path)
+
   def DoesFileExist(self, src):
     """Checks if the given path exists on device target.