Revert 221409 "Fix threading issues in aw form database"

Broke Android Tests:
http://build.chromium.org/p/chromium.linux/buildstatus?builder=Android%20Tests%20%28dbg%29&number=14173

> Fix threading issues in aw form database
> 
> BUG=285584
> 
> Review URL: https://chromiumcodereview.appspot.com/23803005

TBR=sgurun@chromium.org

Review URL: https://codereview.chromium.org/23679005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221423 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 41 insertions, 63 deletions

diff --git a/android_webview/browser/aw_browser_context.cc b/android_webview/browser/aw_browser_context.cc
index 8551e3f..17be0e3 100644
--- a/android_webview/browser/aw_browser_context.cc
+++ b/android_webview/browser/aw_browser_context.cc
@@ -23,8 +23,6 @@
 #include "content/public/browser/web_contents.h"
 #include "net/url_request/url_request_context.h"
 
-using content::BrowserThread;
-
 namespace android_webview {
 
 namespace {
@@ -43,11 +41,11 @@ class AwResourceContext : public content::ResourceContext {
 
   // content::ResourceContext implementation.
   virtual net::HostResolver* GetHostResolver() OVERRIDE {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
     return getter_->GetURLRequestContext()->host_resolver();
   }
   virtual net::URLRequestContext* GetRequestContext() OVERRIDE {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
     return getter_->GetURLRequestContext();
   }
   virtual bool AllowMicAccess(const GURL& origin) OVERRIDE {
@@ -75,9 +73,6 @@ AwBrowserContext::AwBrowserContext(
       user_pref_service_ready_(false) {
   DCHECK(g_browser_context == NULL);
   g_browser_context = this;
-
-  form_database_service_.reset(
-      new AwFormDatabaseService(context_storage_path_));
 }
 
 AwBrowserContext::~AwBrowserContext() {
@@ -151,6 +146,10 @@ AwQuotaManagerBridge* AwBrowserContext::GetQuotaManagerBridge() {
 }
 
 AwFormDatabaseService* AwBrowserContext::GetFormDatabaseService() {
+  if (!form_database_service_) {
+    form_database_service_.reset(
+        new AwFormDatabaseService(context_storage_path_));
+  }
   return form_database_service_.get();
 }
 
diff --git a/android_webview/browser/aw_form_database_service.cc b/android_webview/browser/aw_form_database_service.cc
index 54db3c9..2b168de 100644
--- a/android_webview/browser/aw_form_database_service.cc
+++ b/android_webview/browser/aw_form_database_service.cc
@@ -4,13 +4,11 @@
 
 #include "android_webview/browser/aw_form_database_service.h"
 #include "base/logging.h"
-#include "base/synchronization/waitable_event.h"
 #include "components/autofill/core/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 base::WaitableEvent;
 using content::BrowserThread;
 
 namespace {
@@ -25,7 +23,10 @@ void DatabaseErrorCallback(sql::InitStatus status) {
 
 namespace android_webview {
 
-AwFormDatabaseService::AwFormDatabaseService(const base::FilePath path) {
+AwFormDatabaseService::AwFormDatabaseService(const base::FilePath path)
+    : pending_query_handle_(0),
+      has_form_data_(false),
+      completion_(false, false) {
 
   web_database_ = new WebDatabaseService(path.Append(kWebDataFilename),
       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI),
@@ -41,33 +42,30 @@ AwFormDatabaseService::AwFormDatabaseService(const base::FilePath path) {
 }
 
 AwFormDatabaseService::~AwFormDatabaseService() {
+  CancelPendingQuery();
   Shutdown();
 }
 
 void AwFormDatabaseService::Shutdown() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(result_map_.empty());
-  // TODO(sgurun) we don't run into this logic right now,
-  // but if we do, then we need to implement cancellation
-  // of pending queries.
   autofill_data_->ShutdownOnUIThread();
   web_database_->ShutdownDatabase();
 }
 
+void AwFormDatabaseService::CancelPendingQuery() {
+  if (pending_query_handle_) {
+    if (autofill_data_.get())
+      autofill_data_->CancelRequest(pending_query_handle_);
+    pending_query_handle_ = 0;
+  }
+}
+
 scoped_refptr<autofill::AutofillWebDataService>
 AwFormDatabaseService::get_autofill_webdata_service() {
   return autofill_data_;
 }
 
 void AwFormDatabaseService::ClearFormData() {
-  BrowserThread::PostTask(
-      BrowserThread::DB,
-      FROM_HERE,
-      base::Bind(&AwFormDatabaseService::ClearFormDataImpl,
-                 base::Unretained(this)));
-}
-
-void AwFormDatabaseService::ClearFormDataImpl() {
   base::Time begin;
   base::Time end = base::Time::Max();
   autofill_data_->RemoveFormElementsAddedBetween(begin, end);
@@ -75,50 +73,35 @@ void AwFormDatabaseService::ClearFormDataImpl() {
 }
 
 bool AwFormDatabaseService::HasFormData() {
-  WaitableEvent completion(false, false);
-  bool result = false;
-  BrowserThread::PostTask(
-      BrowserThread::DB,
-      FROM_HERE,
+  BrowserThread::PostTask(BrowserThread::DB, FROM_HERE,
       base::Bind(&AwFormDatabaseService::HasFormDataImpl,
-                 base::Unretained(this),
-                 &completion,
-                 &result));
-  completion.Wait();
-  return result;
+                 base::Unretained(this)));
+  completion_.Wait();
+  return has_form_data_;
 }
 
-void AwFormDatabaseService::HasFormDataImpl(
-    WaitableEvent* completion,
-    bool* result) {
-  WebDataServiceBase::Handle pending_query_handle =
-      autofill_data_->HasFormElements(this);
-  PendingQuery query;
-  query.result = result;
-  query.completion = completion;
-  result_map_[pending_query_handle] = query;
+void AwFormDatabaseService::HasFormDataImpl() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  pending_query_handle_ = autofill_data_->HasFormElements(this);
 }
 
+
 void AwFormDatabaseService::OnWebDataServiceRequestDone(
     WebDataServiceBase::Handle h,
     const WDTypedResult* result) {
 
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
-  bool has_form_data = false;
+  DCHECK_EQ(pending_query_handle_, h);
+  pending_query_handle_ = 0;
+  has_form_data_ = false;
+
   if (result) {
     DCHECK_EQ(AUTOFILL_VALUE_RESULT, result->GetType());
     const WDResult<bool>* autofill_result =
         static_cast<const WDResult<bool>*>(result);
-    has_form_data = autofill_result->GetValue();
-  }
-  QueryMap::const_iterator it = result_map_.find(h);
-  if (it == result_map_.end()) {
-    LOG(WARNING) << "Received unexpected callback from web data service";
-    return;
+    has_form_data_ = autofill_result->GetValue();
   }
-  *(it->second.result) = has_form_data;
-  it->second.completion->Signal();
-  result_map_.erase(h);
+  completion_.Signal();
 }
 
 }  // namespace android_webview
diff --git a/android_webview/browser/aw_form_database_service.h b/android_webview/browser/aw_form_database_service.h
index d0b7b48..c1cbc37 100644
--- a/android_webview/browser/aw_form_database_service.h
+++ b/android_webview/browser/aw_form_database_service.h
@@ -7,14 +7,11 @@
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
+#include "base/synchronization/waitable_event.h"
 #include "components/autofill/core/browser/webdata/autofill_webdata_service.h"
 #include "components/webdata/common/web_data_service_consumer.h"
 #include "components/webdata/common/web_database_service.h"
 
-namespace base {
-class WaitableEvent;
-};
-
 namespace android_webview {
 
 // Handles the database operations necessary to implement the autocomplete
@@ -45,16 +42,15 @@ class AwFormDatabaseService : public WebDataServiceConsumer {
       const WDTypedResult* result) OVERRIDE;
 
  private:
-  struct PendingQuery {
-    bool* result;
-    base::WaitableEvent* completion;
-  };
-  typedef std::map<WebDataServiceBase::Handle, PendingQuery> QueryMap;
+  // Cancels the currently pending WebDataService query, if there is one.
+  void CancelPendingQuery();
 
-  void ClearFormDataImpl();
-  void HasFormDataImpl(base::WaitableEvent* completion, bool* result);
+  void HasFormDataImpl();
 
-  QueryMap result_map_;
+  // Stores the query handle when an async database query is executed.
+  WebDataServiceBase::Handle pending_query_handle_;
+  bool has_form_data_;
+  base::WaitableEvent completion_;
 
   scoped_refptr<autofill::AutofillWebDataService> autofill_data_;
   scoped_refptr<WebDatabaseService> web_database_;