Initialize POD members of ApplicationManager, and other drive-by's.

In particular, disable_cache_ is flapping in the wind. It's not actually
a bug "in real life" (i.e., the Context initializes it by calling
set_disable_cache()), but makes you wonder about, e.g., the tests for
ApplicationManager.

R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/1123263004
diff --git a/shell/application_manager/application_manager.cc b/shell/application_manager/application_manager.cc
index abaa11a..dd9b0be 100644
--- a/shell/application_manager/application_manager.cc
+++ b/shell/application_manager/application_manager.cc
@@ -19,7 +19,6 @@
 #include "shell/application_manager/network_fetcher.h"
 #include "shell/application_manager/query_util.h"
 #include "shell/application_manager/shell_impl.h"
-#include "shell/switches.h"
 
 using mojo::Application;
 using mojo::ApplicationPtr;
@@ -97,7 +96,10 @@
 }
 
 ApplicationManager::ApplicationManager(Delegate* delegate)
-    : delegate_(delegate), weak_ptr_factory_(this) {
+    : delegate_(delegate),
+      blocking_pool_(nullptr),
+      disable_cache_(false),
+      weak_ptr_factory_(this) {
 }
 
 ApplicationManager::~ApplicationManager() {