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 "chrome/common/instant_types.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace chrome {
+namespace search {
+struct Mode;
+}
+}
+
+namespace content {
+class WebContents;
+}
+
+namespace gfx {
+class Rect;
+}
+
+// InstantClient is used to exchange messages between its delegate and a page
+// that supports the Instant API (http://dev.chromium.org/searchbox).
+class InstantClient : public content::WebContentsObserver {
+ public:
+  // When InstantClient receives messages from the page, it calls the following
+  // methods on its delegate.
+  class Delegate {

[sky, 2012/12/03 22:22:23]

The style guide says classes like this should be in their owner header: "Prefer
putting delegate classes in their own header files. Implementors of the delegate
interface will often be included elsewhere, which will often cause more coupling
with the header of the main class."

Also, add a virtual destructor in the protected section.

[sreeram, 2012/12/04 08:10:52]

Right. However, all the implementors of this interface include instant_client.h
anyway (because they each have an "InstantClient client_;" object member). So I
didn't see the value in separating this out. Let me know if you still feel
strongly.
Done.

+   public:
+    // Called when the page has suggestions. Usually in response to Change(),
+    // SendAutocompleteResults() or UpOrDownKeyPressed().
+    virtual void SetSuggestions(
+        const std::vector<InstantSuggestion>& suggestions) = 0;
+
+    // Called upon determination of Instant API support. Usually in response to
+    // SetContents() or when the page first finishes loading.
+    virtual void InstantSupportDetermined(bool supports_instant) = 0;
+
+    // Called when the page wants to be shown. Usually in response to Change(),
+    // SendAutocompleteResults() or SearchModeChanged().
+    virtual void ShowInstantPreview(InstantShownReason reason,
+                                    int height,
+                                    InstantSizeUnits units) = 0;
+  };
+
+  // Doesn't take ownership of |delegate|.
+  explicit InstantClient(Delegate* delegate);
+  virtual ~InstantClient();

[sky, 2012/12/03 22:22:23]

Does this need to be virtual?

[sreeram, 2012/12/04 08:10:52]

No. But without it, the clang style plugin or some such gives an error saying
that "all classes that override a virtual method must have a virtual destructor"
(and this class does have a couple of OVERRIDE declarations).

+
+  // Sets |contents| as the page to communicate with. |contents| can be NULL,
+  // which effectively stops all communication.
+  void SetContents(content::WebContents* contents);
+
+  // Tells the page that the user typed |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, |text| is taken as the
+  // exact query (no prediction is made).
+  void Update(const string16& text, bool verbatim);
+
+  // Tells the page that the user pressed Enter in the omnibox.
+  void Submit(const string16& text);
+
+  // Tells the page that the user clicked on it.

[samarth, 2012/12/03 19:46:03]

A little more explanation please. Otherwise the comment is confusing (why does
clicking on the page cause Cancel()?)

[sreeram, 2012/12/04 08:10:52]

Done.

+  void Cancel(const string16& text);
+
+  // Tells the page the bounds of the omnibox dropdown (in screen coordinates).
+  // This is used by the page to offset the results to avoid them being covered
+  // by the omnibox dropdown.
+  void SetOmniboxBounds(const gfx::Rect& bounds);
+
+  // Tells the renderer to determine if the page supports the Instant API, which
+  // results in a call to InstantSupportDetermined() when the reply is received.
+  void DetermineIfPageSupportsInstant();
+
+  // 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);
+
+  // Tells the page that the active tab's search mode has changed.
+  void SearchModeChanged(const chrome::search::Mode& mode);
+
+  // Tells the page about the current theme background.
+  void SendThemeBackgroundInfo(const ThemeBackgroundInfo& theme_info);
+
+  // Tells the page about the current theme area height.
+  void SendThemeAreaHeight(int height);
+
+ 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;
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+
+  void SetSuggestions(int page_id,
+                      const std::vector<InstantSuggestion>& suggestions);
+  void InstantSupportDetermined(int page_id, bool result);
+  void ShowInstantPreview(int page_id,
+                          InstantShownReason reason,
+                          int height,
+                          InstantSizeUnits units);
+
+  Delegate* const delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(InstantClient);
+};
+
+#endif  // CHROME_BROWSER_INSTANT_INSTANT_CLIENT_H_