[Android] Allow setting recently visited search engines as default search engine

chrome/browser/search_engines/template_url_service_android.h

Index: chrome/browser/search_engines/template_url_service_android.h
diff --git a/chrome/browser/search_engines/template_url_service_android.h b/chrome/browser/search_engines/template_url_service_android.h
index af5f38c08a212727731e298448ae5df747711b74..37c3a16ab53f1be1a594c93b63d16ffc7e84e8c9 100644
--- a/chrome/browser/search_engines/template_url_service_android.h
+++ b/chrome/browser/search_engines/template_url_service_android.h
@@ -27,18 +27,22 @@ class TemplateUrlServiceAndroid : public TemplateURLServiceObserver {
   void SetUserSelectedDefaultSearchProvider(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
-      jint selected_index);
-  jint GetDefaultSearchProvider(
+      const base::android::JavaParamRef<jstring>& jkeyword);
+
+  jint GetDefaultSearchProviderIndex(
       JNIEnv* env,
-      const base::android::JavaParamRef<jobject>& obj);
-  jint GetTemplateUrlCount(JNIEnv* env,
-                           const base::android::JavaParamRef<jobject>& obj);
-  jboolean IsLoaded(JNIEnv* env,
-                    const base::android::JavaParamRef<jobject>& obj);
+      const base::android::JavaParamRef<jobject>& obj) const;
+
+  jint GetTemplateUrlCount(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj) const;
+  jboolean IsLoaded(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj) const;
   base::android::ScopedJavaLocalRef<jobject> GetTemplateUrlAt(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
-      jint index);
+      jint index) const;
   jboolean IsSearchProviderManaged(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj);
@@ -71,20 +75,22 @@ class TemplateUrlServiceAndroid : public TemplateURLServiceObserver {
   base::android::ScopedJavaLocalRef<jstring> GetSearchEngineUrlFromTemplateUrl(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
-      jint index);
+      const base::android::JavaParamRef<jstring>& jkeyword);
 
   static bool Register(JNIEnv* env);
 
  private:
   ~TemplateUrlServiceAndroid() override;
 
-  bool IsPrepopulatedTemplate(TemplateURL* url);
-
   void OnTemplateURLServiceLoaded();
 
   // TemplateUrlServiceObserver:
   void OnTemplateURLServiceChanged() override;
 
+  // Retrieves and sorts TemplateURL list and calculates the index of the
+  // default search provider with it.

[Peter Kasting, 2016/11/29 03:32:18]

This comment is incorrect, since the function does not calculate a default
search provider index.

There have been several cases in this CL where comments haven't been updated
correctly from one patch set to another.  Please be careful to keep your
comments up to date.  Reviewers now and readers later will treat your comments
as more important than the code itself.

I don't know whether you should clarify the "sorts" bit at all.  Perhaps a
comment like this:

Updates |template_urls_| to contain everything for which
TemplateURLService::ShowInDefaultList() returns true.  Sorts this list with
prepopulated engines first, then any default non-prepopulated engine, then other
non-prepopulated engines.

[ltian, 2016/11/30 06:36:17]

Sorry for forgetting update the comment up to date. And the |template_urls_|
actually not only holds urls for which TemplateURLService::ShowInDefaultList()
returns true, but also all the other Template URLs.

+  void LoadTemplateURLs();
+
   JavaObjectWeakGlobalRef weak_java_obj_;
 
   // Pointer to the TemplateUrlService for the main profile.
@@ -92,6 +98,10 @@ class TemplateUrlServiceAndroid : public TemplateURLServiceObserver {
 
   std::unique_ptr<TemplateURLService::Subscription> template_url_subscription_;
 
+  // Caches the up-to-date TemplateURL list so that calls from Android could
+  // directly get data from it.
+  std::vector<TemplateURL*> template_urls_;
+
   DISALLOW_COPY_AND_ASSIGN(TemplateUrlServiceAndroid);
 };