[ntp4] Use highest quality jpeg compression for thumbnail images.

chrome/browser/history/top_sites.cc

 // Copyright (c) 2011 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/history/top_sites.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 41 matching lines @@
 // temp_images_ for details.
 static const size_t kMaxTempTopImages = 8;
 
 static const int kDaysOfHistory = 90;
 // Time from startup to first HistoryService query.
 static const int64 kUpdateIntervalSecs = 15;
 // Intervals between requests to HistoryService.
 static const int64 kMinUpdateIntervalMinutes = 1;
 static const int64 kMaxUpdateIntervalMinutes = 60;
 
+// Use 100 quality (highest quality) because we're very sensitive to
+// artifacts for these small sized, highly detailed images.
+static const int kTopSitesImageQuality = 100;
+
 const TopSites::PrepopulatedPage kPrepopulatedPages[] = {
   { IDS_CHROME_WELCOME_URL, IDS_NEW_TAB_CHROME_WELCOME_PAGE_TITLE,
     IDR_PRODUCT_LOGO_16, IDR_NEWTAB_CHROME_WELCOME_PAGE_THUMBNAIL,
     SkColorSetRGB(0, 147, 60) },
   { IDS_WEBSTORE_URL, IDS_NEW_TAB_CHROME_WELCOME_PAGE_TITLE,
     IDR_WEBSTORE_ICON_16, IDR_NEWTAB_WEBSTORE_THUMBNAIL,
     SkColorSetRGB(63, 132, 197) }
 };
 
 namespace {
@@ skipping 540 matching lines @@
   return true;
 }
 
 // static
 bool TopSites::EncodeBitmap(gfx::Image* bitmap,
                             scoped_refptr<RefCountedBytes>* bytes) {
   if (!bitmap)
     return false;
   *bytes = new RefCountedBytes();
   std::vector<unsigned char> data;
-  if (!gfx::JPEGEncodedDataFromImage(*bitmap, &data))
+  if (!gfx::JPEGEncodedDataFromImage(*bitmap, kTopSitesImageQuality, &data))
     return false;
 
   // As we're going to cache this data, make sure the vector is only as big as
   // it needs to be, as JPEGCodec::Encode() over-allocates data.capacity().
   // (In a C++0x future, we can just call shrink_to_fit() in Encode())
   (*bytes)->data() = data;
   return true;
 }
 
 void TopSites::RemoveTemporaryThumbnailByURL(const GURL& url) {
@@ skipping 399 matching lines @@
   SetTopSites(pages);
 
   // Used only in testing.
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_TOP_SITES_UPDATED,
       content::Source<TopSites>(this),
       content::Details<CancelableRequestProvider::Handle>(&handle));
 }
 
 }  // namespace history