Make Google Search autocomplete provider cursor aware.

chrome/browser/autocomplete/autocomplete_input.h

Index: chrome/browser/autocomplete/autocomplete_input.h
diff --git a/chrome/browser/autocomplete/autocomplete_input.h b/chrome/browser/autocomplete/autocomplete_input.h
index 67e0bdc73e31c5d60cf24b5beee75eaccfe2933c..6fdecf7b45c0b75e56dec0d0d778a54301689696 100644
--- a/chrome/browser/autocomplete/autocomplete_input.h
+++ b/chrome/browser/autocomplete/autocomplete_input.h
@@ -47,7 +47,29 @@ class AutocompleteInput {
   };
 
   AutocompleteInput();
+  // |text| and |cursor_position| represent the input query and location of
+  // the cursor with the query respectively.

[Peter Kasting, 2012/12/05 20:49:38]

Nit: Add "|cursor_position| may be set to string16::npos if the input string
doesn't come directly from the user's typing."

[Bart N., 2012/12/06 21:43:32]

Done.

[Bart N., 2012/12/06 21:43:32]

Done.

+  //
+  // |prevent_inline_autocomplete| is true if the generated result set should
+  // not require inline autocomplete for the default match.  This is difficult
+  // to explain in the abstract; the practical use case is that after the user
+  // deletes text in the edit, the HistoryURLProvider should make sure not to
+  // promote a match requiring inline autocomplete too highly.
+  //
+  // |prefer_keyword| should be true when the keyword UI is onscreen; this will
+  // bias the autocomplete result set toward the keyword provider when the input
+  // string is a bare keyword.
+  //
+  // |allow_exact_keyword_match| should be false when triggering keyword mode on
+  // the input string would be surprising or wrong, e.g. when highlighting text
+  // in a page and telling the browser to search for it or navigate to it. This
+  // parameter only applies to substituting keywords.
+
+  // If |matches_requested| is BEST_MATCH or SYNCHRONOUS_MATCHES the controller
+  // asks the providers to only return matches which are synchronously
+  // available, which should mean that all providers will be done immediately.
   AutocompleteInput(const string16& text,
+                    size_t cursor_position,
                     const string16& desired_tld,
                     bool prevent_inline_autocomplete,
                     bool prefer_keyword,
@@ -56,7 +78,8 @@ class AutocompleteInput {
   ~AutocompleteInput();
 
   // If type is |FORCED_QUERY| and |text| starts with '?', it is removed.
-  static void RemoveForcedQueryStringIfNecessary(Type type, string16* text);
+  // Returns number of leading characters removed.
+  static size_t RemoveForcedQueryStringIfNecessary(Type type, string16* text);
 
   // Converts |type| to a string representation.  Used in logging.
   static std::string TypeToString(Type type);
@@ -97,10 +120,15 @@ class AutocompleteInput {
   // User-provided text to be completed.
   const string16& text() const { return text_; }
 
+  // Returns 0-based cursor position within |text_| or string16::npos if not
+  // used or past the last character.

[Peter Kasting, 2012/12/05 20:49:38]

Seems like for a string "abc", we should allow the following:

|abc -> 0
a|bc -> 1
ab|c -> 2
abc| -> 3

This comment makes it sound like the last case isn't valid, and we just use npos
there.  Isn't there value in distinguishing "cursor at end" from "no cursor --
text didn't come from user typing"?

[Bart N., 2012/12/06 21:43:32]

It isn't a bug, it was done intentionally. However, I consulted searchbox folks,
and it seems that cp is always send from JS (details omitted). We agreed to make
it consistent, so I've just changed the comment as well as the implementation.

+  size_t cursor_position() const { return cursor_position_; }
+
   // Use of this setter is risky, since no other internal state is updated
-  // besides |text_| and |parts_|.  Only callers who know that they're not
-  // changing the type/scheme/etc. should use this.
-  void UpdateText(const string16& text, const url_parse::Parsed& parts);
+  // besides |text_|, |cursor_position_| and |parts_|.  Only callers who know
+  // that they're not changing the type/scheme/etc. should use this.
+  void UpdateText(const string16& text, size_t cursor_position,

[Peter Kasting, 2012/12/05 20:49:38]

Nit: One arg per line

[Bart N., 2012/12/06 21:43:32]

Done.

+                  const url_parse::Parsed& parts);
 
   // User's desired TLD, if one is not already present in the text to
   // autocomplete.  When this is non-empty, it also implies that "www." should
@@ -146,6 +174,7 @@ class AutocompleteInput {
 
  private:
   string16 text_;
+  size_t cursor_position_;
   string16 desired_tld_;
   Type type_;
   url_parse::Parsed parts_;