InstantExtended: Adding InstantRestrictedIDCache.

chrome/common/instant_types.h

Index: chrome/common/instant_types.h
diff --git a/chrome/common/instant_types.h b/chrome/common/instant_types.h
index ae371c9a2a3d27687e26878c7b28fe707c7ce9a7..5e98c47bd8d36905e48aa0d012906bc6c06dacf0 100644
--- a/chrome/common/instant_types.h
+++ b/chrome/common/instant_types.h
@@ -11,6 +11,10 @@
 #include "content/public/common/page_transition_types.h"
 #include "googleurl/src/gurl.h"
 
+// ID used by Instant code to refer to objects (e.g. autocomplete results, most
+// visisted items) that the Instant page needs access to.

[dhollowa, 2013/03/14 00:02:43]

nit: "Autocomplete results", "Most Visited items"

[Shishir, 2013/03/14 19:53:03]

Done.

+typedef int InstantRestrictedID;

[palmer, 2013/03/13 23:50:37]

This should be an unsigned int (it never goes < 0, *and* it's used as an index
into a vector).

[dhollowa, 2013/03/14 00:02:43]

unsigned int

[Shishir, 2013/03/14 19:53:03]

From "base/basictypes.h"

// NOTE: unsigned types are DANGEROUS in loops and other arithmetical
// places.  Use the signed types unless your variable represents a bit
// pattern (eg a hash value) or you really need the extra bit.  Do NOT
// use 'unsigned' to express "this value should always be positive";
// use assertions for this.

I had made this uint first and then changed it after reading this.

[Shishir, 2013/03/14 19:53:03]

Ditto.

[dhollowa, 2013/03/14 23:40:00]

I'm fine with int.

[palmer, 2013/03/15 01:47:53]

That comment is wrong. The problem is when you compare types of different
signedness, not merely the use of unsigned types.

It's especially ironic that they say unsigned types are dangerous in other
arithmetical places" — signed types have *undefined* behavior when the
arithmetic overflows; only unsigned types have defined behavior.

Unsigned integers are the *correct* and *safe* types to use for sizes, offsets,
array and vector indices, and so on. Signed types are affirmatively *unsafe* in
those uses.

[Shishir, 2013/03/15 17:31:15]

With the current code there is no strict requirement that the number can't be
negative. There are no array like accesses any more, no std::max kind of stuff
so I think we can leave it an int.

+
 // Ways that the Instant suggested text is autocompleted into the omnibox.
 enum InstantCompleteBehavior {
   // Autocomplete the suggestion immediately.
@@ -72,6 +76,10 @@ struct InstantAutocompleteResult {
   int relevance;
 };
 
+// An InstantAutocompleteResult along with its assigned restricted ID.
+typedef std::pair<InstantRestrictedID, InstantAutocompleteResult>
+    InstantAutocompleteResultIDPair;
+
 // How to interpret the size (height or width) of the Instant overlay (preview).
 enum InstantSizeUnits {
   // As an absolute number of pixels.
@@ -153,11 +161,6 @@ struct ThemeBackgroundInfo {
 };
 
 struct InstantMostVisitedItem {
-  InstantMostVisitedItem() : most_visited_item_id(0) {}
-
-  // A private identifier used on the browser side when retrieving assets.
-  uint64 most_visited_item_id;
-
   // The URL of the Most Visited item.
   GURL url;
 
@@ -166,4 +169,8 @@ struct InstantMostVisitedItem {
   string16 title;
 };
 
+// An InstantMostVisitedItem along with its assigned restricted ID.
+typedef std::pair<InstantRestrictedID, InstantMostVisitedItem>
+    InstantMostVisitedItemIDPair;
+
 #endif  // CHROME_COMMON_INSTANT_TYPES_H_