Implement WebViewDatabase's hasFormData API for chromium based webview.

android_webview/browser/aw_form_database_service.cc

+// Copyright (c) 2013 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 "android_webview/browser/aw_form_database_service.h"
+#include "base/logging.h"
+#include "components/autofill/browser/webdata/autofill_table.h"
+#include "components/webdata/common/webdata_constants.h"
+#include "content/public/browser/browser_thread.h"
+#include "ui/base/l10n/l10n_util_android.h"
+
+using content::BrowserThread;
+
+namespace {
+
+// Callback to handle database error. It seems chrome uses this to
+// display an error dialog box only.
+void DatabaseErrorCallback(sql::InitStatus status) {
+  LOG(WARNING) << "initializing autocomplete database failed";

[benm (inactive), 2013/05/07 11:16:11]

Does the caller of this function then disable autofill functionality? Just
wondering if we need to do anything else here. Maybe we could drop the DB and
try again or something?

[sgurun-gerrit only, 2013/05/07 18:39:02]

the webdata service backend does not issue any queries if the initialization
fails:

  if (db_ && init_status_ == sql::INIT_OK && !request->IsCancelled()) {
    request->SetResult(task.Run(db_.get()).Pass());
  }

as far as I can see, chrome is only showing a UI when init fails. I don't see it
taking any other action:
 // Users of this class may provide a callback to handle errors
  // (e.g. by showing a UI). The callback is called only on error, and
  // takes a single parameter, the sql::InitStatus value from trying
  // to open the database.
  // TODO(joi): Should we combine this with WebDatabaseService::InitCallback?
  typedef base::Callback<void(sql::InitStatus)> ProfileErrorCallback;

// Callback to show error dialog on profile load error.
void ProfileErrorCallback(sql::InitStatus status) {
  ShowProfileErrorDialog(
      (status == sql::INIT_FAILURE) ?
      IDS_COULDNT_OPEN_PROFILE_ERROR : IDS_PROFILE_TOO_NEW_ERROR);
}

     <message name="IDS_COULDNT_OPEN_PROFILE_ERROR" desc="Error displayed on
startup when the profile can not be opened correctly due to problems reading or
writing files in it">
Your profile could not be opened correctly.

Some features may be unavailable.  Please check that the profile exists and you
have permission to read and write its contents."

On 2013/05/07 11:16:11, benm wrote:

+}
+
+}  // namespace
+
+namespace android_webview {
+
+AwFormDatabaseService::AwFormDatabaseService(const base::FilePath path)
+    : pending_query_handle_(0),
+      has_form_elements_(0),

[benm (inactive), 2013/05/07 11:16:11]

0 -> false

[sgurun-gerrit only, 2013/05/07 18:39:02]

Done.

+      completion_(false, false) {
+
+  web_database_ = new WebDatabaseService(path.Append(kWebDataFilename));
+  web_database_->AddTable(

[benm (inactive), 2013/05/07 11:16:11]

Do we need to do this every time that we instantiate this object? We need it
first time to set up the database, but after that it should be taken care of by
LoadDatabase() I think?

[sgurun-gerrit only, 2013/05/07 18:39:02]

I think the issue is that there are lots of abstraction layers hiding what is
going on with the real database. Also the naming does not help.

What we are adding is a WebDatabaseTable, which wraps a database table, to the
backend. A WebDatabaseTable knows how to create a db table if it does not exist
and how to migrate itself to newer versions. It also knows how to run queries to
retrieve data (i.e. such as HasFormElements()). At the initialization time, the
backend iterates over all the WebDatabaseTables and inits them,
creating/migrating tables as necessary. the init routine is called by
LoadDatabase() so we need to add the table before calling it.

If on the other hand what you mean is whether we need to do it more than once
during the lifetime of a process, no we do not. but it is already owned by the
AwBrowserContext, and created once.

On 2013/05/07 11:16:11, benm wrote:

+      scoped_ptr<WebDatabaseTable>(new autofill::AutofillTable(
+          l10n_util::GetDefaultLocale())));
+  web_database_->LoadDatabase();
+
+  autofill_data_ = new autofill::AutofillWebDataService(
+      web_database_, base::Bind(&DatabaseErrorCallback));
+  autofill_data_->Init();
+}
+
+AwFormDatabaseService::~AwFormDatabaseService() {
+  CancelPendingQuery();

[benm (inactive), 2013/05/07 11:16:11]

Shutdown() too?

[sgurun-gerrit only, 2013/05/07 18:41:59]

Done.

+}
+
+void AwFormDatabaseService::Shutdown() {
+  autofill_data_->ShutdownOnUIThread();

[benm (inactive), 2013/05/07 11:16:11]

DCHECK that we're on the UI thread.

[sgurun-gerrit only, 2013/05/07 18:39:02]

Done.

+  web_database_->ShutdownDatabase();
+}
+
+void AwFormDatabaseService::CancelPendingQuery() {
+  if (pending_query_handle_) {
+    if (autofill_data_)
+      autofill_data_->CancelRequest(pending_query_handle_);
+    pending_query_handle_ = 0;
+  }
+}
+
+scoped_refptr<autofill::AutofillWebDataService>
+AwFormDatabaseService::get_autofill_webdata_service() {
+  return autofill_data_;
+}
+
+void AwFormDatabaseService::ClearFormElements() {
+

[benm (inactive), 2013/05/07 11:16:11]

nit: remove \n (and throughout)

[sgurun-gerrit only, 2013/05/07 18:39:02]

Done.

+  base::Time begin;
+  base::Time end = base::Time::Max();
+  autofill_data_->RemoveFormElementsAddedBetween(begin, end);
+  autofill_data_->RemoveAutofillDataModifiedBetween(begin, end);
+}
+
+bool AwFormDatabaseService::HasFormElements() {
+
+  BrowserThread::PostTask(BrowserThread::DB, FROM_HERE,
+      base::Bind(&AwFormDatabaseService::HasFormElementsImpl,
+                 base::Unretained(this)));
+  completion_.Wait();
+  return has_form_elements_;
+}
+
+void AwFormDatabaseService::HasFormElementsImpl() {
+
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  has_form_elements_ = false;
+  pending_query_handle_ = autofill_data_->HasFormElements(this);
+}
+
+
+void AwFormDatabaseService::OnWebDataServiceRequestDone(
+    WebDataServiceBase::Handle h,
+    const WDTypedResult* result) {
+
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  DCHECK_EQ(pending_query_handle_, h);
+  pending_query_handle_ = 0;
+
+  if (result) {
+    DCHECK_EQ(AUTOFILL_VALUE_RESULT, result->GetType());
+    const WDResult<bool>* autofill_result =
+        static_cast<const WDResult<bool>*>(result);
+    has_form_elements_ = autofill_result->GetValue();
+  }
+  completion_.Signal();
+}
+
+}  // namespace android_webview