Creating a skeleton for Google Now for Chrome implementation.

chrome/browser/ui/google_now/google_now_service.cc

Index: chrome/browser/ui/google_now/google_now_service.cc
diff --git a/chrome/browser/ui/google_now/google_now_service.cc b/chrome/browser/ui/google_now/google_now_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7ba54712b0d27d4fc5c4e9368414c9c6ef45b337
--- /dev/null
+++ b/chrome/browser/ui/google_now/google_now_service.cc
@@ -0,0 +1,119 @@
+// Copyright (c) 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.
+
+#include "chrome/browser/ui/google_now/google_now_service.h"
+#include "content/public/common/geoposition.h"
+
+using base::TimeDelta;
+using content::Geoposition;
+using net::URLRequest;
+
+namespace {
+// Period for polling for Google Now cards to use when the period from the
+// server is not available.
+const int kDefaultPollingPeriodMs = 300000;

[skare_, 2012/12/01 03:00:14]

(optional) add comment
... = 300000;  // 5 minutes

[vadimt, 2012/12/03 18:48:07]

Done.

+}  // namespace
+
+struct GoogleNowService::ServerResponse {
+  // TODO(vadimt): Populate this structure with real fields.
+  int next_request_delay_ms;
+};
+
+GoogleNowService::GoogleNowService(Profile* profile)
+    : profile_(profile) {
+  DCHECK(profile_);
+}
+
+void GoogleNowService::Init() {
+  // If Google Now integration is enabled for the profile, start the first cards

[skare_, 2012/12/01 03:00:14]

nit: code sort of explains itself here but feel free to keep the comment.

[vadimt, 2012/12/03 18:48:07]

Thanks! I'll keep the comment, more info doesn't hurt :)

+  // update.
+  if (IsGoogleNowEnabled())
+    UpdateCards();
+}
+
+void GoogleNowService::StartWaitingForNextUpdate(int64 delay_ms) {
+  DCHECK(!next_update_timer_.IsRunning());
+
+  next_update_timer_.Start(FROM_HERE, TimeDelta::FromMilliseconds(delay_ms),
+                           this, &GoogleNowService::OnWaitingForNextUpdateEnds);
+}
+
+void GoogleNowService::OnWaitingForNextUpdateEnds() {
+  DCHECK(IsGoogleNowEnabled());
+  DCHECK(!next_update_timer_.IsRunning());
+
+  UpdateCards();
+}
+
+bool GoogleNowService::IsGoogleNowEnabled() const {
+  // TODO(vadimt): Return a value indicating whether Google Now integration is
+  // enable for 'profile_'.
+  // TODO(vadimt): Process enabling and disabling Google Now integration while
+  // the service is running.
+  return true;
+}
+
+void GoogleNowService::UpdateCards() {
+  // Start obtaining geolocation for the server's request.
+  StartObtainingGeolocation();
+}
+
+void GoogleNowService::StartObtainingGeolocation() {
+  // TODO(vadimt): Implement via making a geolocation request.
+  OnLocationObtained(Geoposition());
+}
+
+bool GoogleNowService::IsLocationGood(const content::Geoposition& position) {
+  // TODO(vadimt): Check the location's fields to see whether it's usable.
+  return true;
+}
+
+void GoogleNowService::OnLocationObtained(const Geoposition& position) {
+  DCHECK(IsGoogleNowEnabled());
+  DCHECK(!next_update_timer_.IsRunning());
+
+  if (IsLocationGood(position)) {
+    StartServerRequest(position);
+  } else {
+    // If the location is bad, schedule next cards update.
+    StartWaitingForNextUpdate(kDefaultPollingPeriodMs);
+  }
+}
+
+void GoogleNowService::StartServerRequest(
+    const content::Geoposition& position) {
+  // TODO(vadimt): Implement via making URLRequest to the server.
+  OnServerRequestCompleted(NULL, 0);
+}
+
+void GoogleNowService::OnServerRequestCompleted(URLRequest* request,
+                                                int num_bytes) {
+  DCHECK(IsGoogleNowEnabled());
+  DCHECK(!next_update_timer_.IsRunning());
+
+  ServerResponse server_response;
+  // TODO(vadimt): Check request's status.
+  if (ParseServerResponse(request, num_bytes, &server_response)) {
+    ShowNotifications(server_response);
+    // Once the cards are shown, schedule next cards update after the delay
+    // suggested by the server.
+    StartWaitingForNextUpdate(server_response.next_request_delay_ms);
+  } else {
+    // If the server response is bad, schedule next cards update after the
+    // default delay.

[skare_, 2012/12/01 03:00:14]

You may want exponential backoff with randomized jitter in the error case (or a
TODO for the functionality), so that if the server gets DDOSed you don't have
that same collection of clients hitting the server simultaneously one interval
later.

Chrome may have reusable code to facilitate this (not sure; Toolbar does, for
example).

This is assuming ServerResponse won't handle all network-related issues itself.

[vadimt, 2012/12/03 18:48:07]

Done.

+    StartWaitingForNextUpdate(kDefaultPollingPeriodMs);
+  }
+}
+
+bool GoogleNowService::ParseServerResponse(const URLRequest* request,
+    int num_bytes, ServerResponse* server_response) {
+  // TODO(vadimt): Do real parsing.
+  server_response->next_request_delay_ms = 10000;// TODO 300000;

[skare_, 2012/12/01 03:00:14]

I know this will come from the response, but maybe use kDefaultPollingPeriodMs
as the constant (and remove the TODO) for now?

[vadimt, 2012/12/03 18:48:07]

Done.

+  return true;
+}
+
+void GoogleNowService::ShowNotifications(
+    const ServerResponse& server_response) {
+  // TODO(vadimt): Implement via using Chrome Notifications.

[skare_, 2012/12/01 03:00:14]

nit: just one (either) of "via using"

[vadimt, 2012/12/03 18:48:07]

Done.

+}