Make ThumbnailStore broadcast a notification when it has finished reading thumbnails from disk.

Make DOMUIThumbnailSource wait for this notification if ThumbnailStore isn't ready yet.
Also clean up some of the code.

Review URL: http://codereview.chromium.org/155911

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21785 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 64 insertions, 13 deletions

diff --git a/chrome/browser/dom_ui/dom_ui_thumbnail_source.cc b/chrome/browser/dom_ui/dom_ui_thumbnail_source.cc
index 5a10c7c..230389b 100644
--- a/chrome/browser/dom_ui/dom_ui_thumbnail_source.cc
+++ b/chrome/browser/dom_ui/dom_ui_thumbnail_source.cc
@@ -10,6 +10,7 @@
 #include "chrome/browser/profile.h"
 #include "chrome/browser/thumbnail_store.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/notification_service.h"
 #include "chrome/common/url_constants.h"
 #include "googleurl/src/gurl.h"
 #include "grit/theme_resources.h"
@@ -23,20 +24,18 @@ DOMUIThumbnailSource::DOMUIThumbnailSource(Profile* profile)
 void DOMUIThumbnailSource::StartDataRequest(const std::string& path,
                                             int request_id) {
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kThumbnailStore)) {
-    RefCountedBytes* data = NULL;
     scoped_refptr<ThumbnailStore> store_ = profile_->GetThumbnailStore();
 
-    if (store_->GetPageThumbnail(GURL(path), &data)) {
-      // Got the thumbnail.
-      SendResponse(request_id, data);
-    } else {
-      // Don't have the thumbnail so return the default thumbnail.
-      if (!default_thumbnail_.get()) {
-        default_thumbnail_ = new RefCountedBytes;
-        ResourceBundle::GetSharedInstance().LoadImageResourceBytes(
-            IDR_DEFAULT_THUMBNAIL, &default_thumbnail_->data);
+    if (!store_->IsReady()) {
+      // Register to be notified when the ThumbnailStore is ready.
+      if (registrar_.IsEmpty()) {
+        registrar_.Add(this, NotificationType::THUMBNAIL_STORE_READY,
+            Source<ThumbnailStore>(store_.get()));
       }
-      SendResponse(request_id, default_thumbnail_);
+      // Insert into pending_requests.
+      pending_requests_.push_back(std::make_pair(path, request_id));
+    } else {
+      DoDataRequest(path, request_id);
     }
     return;
   }  // end --thumbnail-store switch
@@ -55,6 +54,24 @@ void DOMUIThumbnailSource::StartDataRequest(const std::string& path,
   }
 }
 
+void DOMUIThumbnailSource::DoDataRequest(const std::string& path,
+                                         int request_id) {
+  RefCountedBytes* data = NULL;
+  scoped_refptr<ThumbnailStore> store_ = profile_->GetThumbnailStore();
+  if (store_->GetPageThumbnail(GURL(path), &data)) {
+    // Got the thumbnail.
+    SendResponse(request_id, data);
+  } else {
+    // Don't have the thumbnail so return the default thumbnail.
+    if (!default_thumbnail_.get()) {
+      default_thumbnail_ = new RefCountedBytes;
+      ResourceBundle::GetSharedInstance().LoadImageResourceBytes(
+          IDR_DEFAULT_THUMBNAIL, &default_thumbnail_->data);
+    }
+    SendResponse(request_id, default_thumbnail_);
+  }
+}
+
 void DOMUIThumbnailSource::OnThumbnailDataAvailable(
     HistoryService::Handle request_handle,
     scoped_refptr<RefCountedBytes> data) {
@@ -74,3 +91,20 @@ void DOMUIThumbnailSource::OnThumbnailDataAvailable(
     SendResponse(request_id, default_thumbnail_);
   }
 }
+
+void DOMUIThumbnailSource::Observe(NotificationType type,
+                                   const NotificationSource& source,
+                                   const NotificationDetails& details) {
+  if (type.value != NotificationType::THUMBNAIL_STORE_READY) {
+    NOTREACHED();
+    return;
+  }
+
+  // This notification is sent only once.
+  registrar_.RemoveAll();
+
+  for (size_t i = 0; i < pending_requests_.size(); ++i)
+    DoDataRequest(pending_requests_[i].first, pending_requests_[i].second);
+
+  pending_requests_.clear();
+}
diff --git a/chrome/browser/dom_ui/dom_ui_thumbnail_source.h b/chrome/browser/dom_ui/dom_ui_thumbnail_source.h
index c94967b..4e1555d 100644
--- a/chrome/browser/dom_ui/dom_ui_thumbnail_source.h
+++ b/chrome/browser/dom_ui/dom_ui_thumbnail_source.h
@@ -5,20 +5,22 @@
 #ifndef CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 #define CHROME_BROWSER_DOM_UI_DOM_UI_THUMBNAIL_SOURCE_H_
 
-#include <set>
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
 #include "chrome/browser/dom_ui/chrome_url_data_manager.h"
 #include "chrome/browser/history/history.h"
+#include "chrome/common/notification_registrar.h"
 
 class Profile;
 class ThumbnailStore;
 
 // ThumbnailSource is the gateway between network-level chrome:
 // requests for thumbnails and the history backend that serves these.
-class DOMUIThumbnailSource : public ChromeURLDataManager::DataSource {
+class DOMUIThumbnailSource : public ChromeURLDataManager::DataSource,
+                             public NotificationObserver {
  public:
   explicit DOMUIThumbnailSource(Profile* profile);
 
@@ -37,6 +39,14 @@ class DOMUIThumbnailSource : public ChromeURLDataManager::DataSource {
                                 scoped_refptr<RefCountedBytes> data);
 
  private:
+  // NotificationObserver implementation
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  // Fetch the specified resource.
+  void DoDataRequest(const std::string& path, int request_id);
+
   Profile* profile_;
   CancelableRequestConsumerT<int, 0> cancelable_consumer_;
 
@@ -44,6 +54,13 @@ class DOMUIThumbnailSource : public ChromeURLDataManager::DataSource {
   // database doesn't have a thumbnail for a webpage.
   scoped_refptr<RefCountedBytes> default_thumbnail_;
 
+  // Store requests when the ThumbnailStore isn't ready. When a notification is
+  // received that it is ready, then serve these requests.
+  std::vector<std::pair<std::string, int> > pending_requests_;
+
+  // To register to be notified when the ThumbnailStore is ready.
+  NotificationRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(DOMUIThumbnailSource);
 };