Create a PrefStore in support of Blimp metrics collection.

blimp/engine/common/blimp_pref_store.h

Index: blimp/engine/common/blimp_pref_store.h
diff --git a/android_webview/browser/aw_pref_store.h b/blimp/engine/common/blimp_pref_store.h
similarity index 79%
copy from android_webview/browser/aw_pref_store.h
copy to blimp/engine/common/blimp_pref_store.h
index fd0a9fff8e4e68280d36560c59ca063f6235273c..0e65f3e06da4ce75fb4e333d176102bf98eb0210 100644
--- a/android_webview/browser/aw_pref_store.h
+++ b/blimp/engine/common/blimp_pref_store.h
@@ -1,9 +1,9 @@
-// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_
-#define ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_
+#ifndef BLIMP_ENGINE_COMMON_BLIMP_PREF_STORE_H_
+#define BLIMP_ENGINE_COMMON_BLIMP_PREF_STORE_H_
 
 #include <stdint.h>
 
@@ -15,13 +15,15 @@
 #include "components/prefs/persistent_pref_store.h"
 #include "components/prefs/pref_value_map.h"
 
+namespace blimp {
+namespace engine {
 // A light-weight prefstore implementation that keeps preferences

[Kevin M, 2016/04/14 21:49:50]

Add newline above

[Jess, 2016/04/14 22:59:49]

Done.

 // in a memory backed store. This is not a persistent prefstore -- we
 // subclass the PersistentPrefStore here since it is needed by the
-// PrefService, which in turn is needed by the Autofill component.
-class AwPrefStore : public PersistentPrefStore {
+// PrefService, which in turn is needed by the metrics component.

[Kevin M, 2016/04/14 21:49:50]

Could you reference AwPrefStore as the basis for this class?

Have you considered making this a common class, e.g. InMemoryPrefStore, which
android_webview and Blimp can share?

[Jess, 2016/04/14 22:59:49]

Yes.

I'd been assuming the engine need something more in terms of PrefStore
relatively soon, which is why I copied instead of refactoring.

If that isn't the case, I'm happy to refactor things out. I'd appreciate some
guidance on Chromium best practices for this.  I'm not sure where the code would
live or how best to bring in the android webview folks onboard for the refactor.

+class BlimpPrefStore : public PersistentPrefStore {

[Kevin M, 2016/04/14 21:49:50]

Unit tests?

[Jess, 2016/04/14 22:59:49]

Do you have a specific function or set of function in mind? The parent classes
are doing the heavy lifting.

[Kevin M, 2016/04/15 17:45:38]

Can you inject a test-owned prefs_ and verify that the setters and getters are
passing through the data correctly, and invoking the observers when they should?

  public:
-  AwPrefStore();
+  BlimpPrefStore();
 
   // Overriden from PrefStore.

[Kevin M, 2016/04/14 21:49:50]

PrefStore implementation.

[Jess, 2016/04/14 22:59:49]

Done.

   bool GetValue(const std::string& key,
@@ -50,7 +52,7 @@ class AwPrefStore : public PersistentPrefStore {
   void ClearMutableValues() override {}
 
  protected:
-  ~AwPrefStore() override;
+  ~BlimpPrefStore() override;
 
  private:
   // Stores the preference values.
@@ -58,7 +60,10 @@ class AwPrefStore : public PersistentPrefStore {
 
   base::ObserverList<PrefStore::Observer, true> observers_;
 
-  DISALLOW_COPY_AND_ASSIGN(AwPrefStore);
+  DISALLOW_COPY_AND_ASSIGN(BlimpPrefStore);
 };
 
-#endif  // ANDROID_WEBVIEW_BROWSER_AW_PREF_STORE_H_
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_COMMON_BLIMP_PREF_STORE_H_