[AiS] Add prefetching for Answers images.

chrome/browser/autocomplete/base_search_provider.cc

Index: chrome/browser/autocomplete/base_search_provider.cc
diff --git a/chrome/browser/autocomplete/base_search_provider.cc b/chrome/browser/autocomplete/base_search_provider.cc
index 3d47edadc95ad8d42459c129cb5354b3de578d87..70942a170d9f6bdeebaef813d66031deb1facca2 100644
--- a/chrome/browser/autocomplete/base_search_provider.cc
+++ b/chrome/browser/autocomplete/base_search_provider.cc
@@ -12,6 +12,8 @@
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/autocomplete/answers_image_service.h"
+#include "chrome/browser/autocomplete/answers_image_service_factory.h"
 #include "chrome/browser/autocomplete/autocomplete_provider_listener.h"
 #include "chrome/browser/autocomplete/url_prefix.h"
 #include "chrome/browser/history/history_service.h"
@@ -913,6 +915,7 @@ bool BaseSearchProvider::ParseSuggestResults(const base::Value& root_val,
           // Extract Answers, if provided.
           const base::DictionaryValue* answer_json = NULL;
           if (suggestion_detail->GetDictionary("ansa", &answer_json)) {
+            PrefetchAnswersImages(answer_json);
             std::string contents;
             base::JSONWriter::Write(answer_json, &contents);
             answer_contents = base::UTF8ToUTF16(contents);
@@ -935,6 +938,40 @@ bool BaseSearchProvider::ParseSuggestResults(const base::Value& root_val,
   return true;
 }
 
+void BaseSearchProvider::PrefetchAnswersImages(
+    const base::DictionaryValue* answer_json) {
+  DCHECK(answer_json);
+  const base::ListValue* lines = NULL;
+  answer_json->GetList("l", &lines);
+  if (!lines || lines->GetSize() == 0)
+    return;
+
+  // TODO(groby): Do we want prefetch in incognito?

[Peter Kasting, 2014/06/05 23:42:47]

We don't currently send suggest requests in incognito, so I wouldn't think you
could reach here then.

[groby-ooo-7-16, 2014/06/14 00:22:08]

Done.

+  AnswersImageService* image_service =
+      AnswersImageServiceFactory::GetForBrowserContext(profile_);
+  DCHECK(image_service);
+
+  for (size_t line = 0; line < lines->GetSize(); ++line) {
+    const base::DictionaryValue* imageLine = NULL;
+    lines->GetDictionary(line, &imageLine);
+    if (!imageLine)
+      continue;
+    const base::DictionaryValue* imageData = NULL;
+    imageLine->GetDictionary("i", &imageData);
+    if (!imageData)
+      continue;
+    std::string imageUrl;
+    imageData->GetString("d", &imageUrl);
+
+    // Not having an URL is technically a malformed reply, but crashing seems
+    // overly harsh as response.

[Peter Kasting, 2014/06/05 23:42:47]

This comment doesn't seem necessary -- clearly we have to validate any
server-provided data and never crash, so it doesn't seem important to try and
distinguish this sort of malformation from the cases we handle above.

[groby-ooo-7-16, 2014/06/14 00:22:08]

Removed.

+    if (imageUrl.empty())
+      continue;
+    LOG(ERROR) << "Prefetching image for " << imageUrl;

[Peter Kasting, 2014/06/05 23:42:47]

I don't think you should check this line in.

[groby-ooo-7-16, 2014/06/14 00:22:08]

Done.

+    image_service->Prefetch(GURL(imageUrl));

[Peter Kasting, 2014/06/05 23:42:47]

What if GURL(imageUrl) is invalid?  This can happen for more than just an empty
|imageUrl|.  Either Prefetch() needs to validate its input -- in which case you
don't need the empty() check above, since that will handle that case -- or you
need to validity-check the GURL here (and probably DCHECK that it's valid in
Prefetch()), which will again obviate the need for the empty() check above.

[groby-ooo-7-16, 2014/06/14 00:22:08]

Done.

+  }
+}
+
 void BaseSearchProvider::SortResults(bool is_keyword,
                                      const base::ListValue* relevances,
                                      Results* results) {