Simplify OpenType caps feature detection logic

third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp

Index: third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp b/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp
index de00748ea59c8a4a3d943d536de3e1d297ea96f4..3aab5b09f53dcdd49b60e705a876c4b9ab55f778 100644
--- a/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp
+++ b/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupportMPL.cpp
@@ -29,52 +29,37 @@ bool OpenTypeCapsSupport::supportsOpenTypeFeature(
         || tag == HB_TAG('u', 'n', 'i', 'c')
         || tag == HB_TAG('v', 'e', 'r', 't')));
 
-    bool result = false;
-
     if (!hb_ot_layout_has_substitution(face))
         return false;
 
     // Get the OpenType tag(s) that match this script code
-    const size_t kMaxScriptTags = 4;
-    hb_tag_t scriptTags[kMaxScriptTags] = {
+    hb_tag_t scriptTags[] = {
         HB_TAG_NONE,
         HB_TAG_NONE,
         HB_TAG_NONE,
-        HB_TAG_NONE
     };
     hb_ot_tags_from_script(static_cast<hb_script_t>(script),
         &scriptTags[0],
         &scriptTags[1]);
 
-    // Replace the first remaining NONE with DEFAULT
-    for (size_t i = 0; i < kMaxScriptTags; ++i) {
-        if (scriptTags[i] == HB_TAG_NONE) {
-            scriptTags[i] = HB_OT_TAG_DEFAULT_SCRIPT;
-            break;
-        }
-    }
-
-    // Now check for 'smcp' under the first of those scripts that is present
     const hb_tag_t kGSUB = HB_TAG('G', 'S', 'U', 'B');
-    for (size_t j = 0; j < kMaxScriptTags; ++j) {
-        if (scriptTags[j] == HB_TAG_NONE)
-            break;
+    unsigned scriptIndex = 0;
+    // Identify for which script a GSUB table is available.
+    if (!hb_ot_layout_table_choose_script(face,
+        kGSUB,
+        scriptTags,
+        &scriptIndex,
+        nullptr)) {
+        return false;

[drott, 2016/05/26 08:14:05]

This was not in your original suggestion. I guess I can return early here if we
can't find GSUB for any script?

[behdad, 2016/05/27 17:33:29]

No no.  The return value means something else.  It will be false if default
script was found...  Don't prematurely optimize; the cost if there's no GSUB is
unmeasurable.

+    }
 
-        unsigned scriptIndex;
-        if (hb_ot_layout_table_find_script(face,
-            kGSUB,
-            scriptTags[j],
-            &scriptIndex)) {
-            if (hb_ot_layout_language_find_feature(face, kGSUB,
-                scriptIndex,
-                HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
-                tag, nullptr)) {
-                result = true;
-            }
-            break;
-        }
+    if (hb_ot_layout_language_find_feature(face, kGSUB,
+        scriptIndex,
+        HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
+        tag, nullptr)) {
+        return true;
     }
-    return result;
+    return false;
 }
 
 } // namespace blink