Persist the Instant API to committed search result pages.

chrome/browser/instant/instant_client.h

+// Copyright 2012 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 CHROME_BROWSER_INSTANT_INSTANT_CLIENT_H_
+#define CHROME_BROWSER_INSTANT_INSTANT_CLIENT_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/string16.h"
+#include "content/public/browser/web_contents_observer.h"
+
+struct InstantAutocompleteResult;
+class InstantController;
+struct InstantSuggestion;
+
+namespace content {
+class WebContents;
+}
+
+// InstantClient is used to communicate messages between the InstantController
+// and a page that supports the Instant API (http://dev.chromium.org/searchbox).
+class InstantClient : public content::WebContentsObserver {
+ public:
+  InstantClient(InstantController* controller, content::WebContents* contents);

[samarth, 2012/11/27 18:09:43]

Comment either here for below (where the member is) that this doesn't take
ownership of controller.

[sreeram, 2012/11/29 07:33:19]

Done.

+  virtual ~InstantClient();
+
+  // Tells the Instant page that the user typed |user_text| into the omnibox. If
+  // |verbatim| is false, the page predicts the query the user means to type and
+  // fetches results for the prediction. If |verbatim| is true, |user_text| is
+  // taken as the exact query (no prediction is made).
+  void Update(const string16& user_text, bool verbatim);
+
+  // Tells the page that the user pressed Enter in the omnibox.
+  void Submit(const string16& text);
+
+  // Tells the page about the available autocomplete results.
+  void SendAutocompleteResults(
+      const std::vector<InstantAutocompleteResult>& results);
+
+  // Tells the page that the user pressed Up or Down in the omnibox. |count| is
+  // a repeat count, negative for moving up, positive for moving down.
+  void UpOrDownKeyPressed(int count);
+
+  // Sends a message to the renderer asking it to determine whether the page
+  // supports the Instant API.
+  void DetermineIfPageSupportsInstant();

[sky, 2012/11/27 01:07:51]

Seem weird that this is public.

[sreeram, 2012/11/29 07:33:19]

Done.

+
+  // Returns true if the page is known to support the Instant API. This starts
+  // out false, and becomes true whenever we get any message from the page. Once
+  // true, it never becomes false (the page isn't expected to drop Instant API
+  // support suddenly).
+  bool supports_instant() const { return supports_instant_; }
+
+  content::WebContents* contents() const { return web_contents(); }

[sky, 2012/11/27 01:07:51]

nit: one of:

const content::WebContents* contents() const
content::WebContents* contents()

[sreeram, 2012/11/29 07:33:19]

I don't understand this rule. Are you saying that we can't legitimately return
any non-const pointer from a const method (even if the pointer is NOT to a data
member)? That seems draconian to me. For example, would you similarly restrict
InstantController::GetPreviewContents() from returning a non-const object?

+
+ protected:
+  // Overridden from content::WebContentsObserver:
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+
+  // If the |controller_| hasn't already been notified, tells it whether the
+  // page supports the Instant API.

[sky, 2012/11/27 01:07:51]

You should also add a comment that once invoked with true subsequent calls are
ignored, and why that's ok.

[sreeram, 2012/11/29 07:33:19]

I've moved this stuff into private sections now, and so the comments are in the
.cc files.

+  void NotifyInstantSupportDetermined(bool supports_instant);
+
+  InstantController* const controller_;

[sky, 2012/11/27 01:07:51]

style guide says no protected members.

[sreeram, 2012/11/29 07:33:19]

Done.

+
+ private:
+  // Overridden from content::WebContentsObserver:
+  virtual void DidFinishLoad(
+      int64 frame_id,
+      const GURL& validated_url,
+      bool is_main_frame,
+      content::RenderViewHost* render_view_host) OVERRIDE;
+
+  // Message from the page indicating that it has query suggestions.
+  void OnSetSuggestions(int page_id,
+                        const std::vector<InstantSuggestion>& suggestions);
+
+  // Message from the page determining whether it supports the Instant API.

[Jered, 2012/11/27 18:19:53]

determining -> indicating

[sreeram, 2012/11/29 07:33:19]

Removed. No longer applicable.

+  void OnInstantSupportDetermined(int page_id, bool result);
+
+  bool supports_instant_;
+
+  DISALLOW_COPY_AND_ASSIGN(InstantClient);
+};
+
+#endif  // CHROME_BROWSER_INSTANT_INSTANT_CLIENT_H_