More default text attribute value removal

According to the IA2 spec here:
https://wiki.linuxfoundation.org/accessibility/iaccessible2/textattributes
"If an attribute is not specified and if the table shows that there is a default value, the default value should be assumed."

This makes the a11y tree less noisy, smaller and easier to debug, and is similar to how Firefox works.

Bug: 844147
Change-Id: I3f7827d10d9659e5e758827a806da0b7f6598e41
Reviewed-on: https://chromium-review.googlesource.com/1066112Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560318}

content/browser/accessibility/browser_accessibility_com_win.cc

@@ -1933,7 +1933,8 @@ std::vector<base::string16> BrowserAccessibilityComWin::ComputeTextAttributes()
     unsigned int red = SkColorGetR(color);
     unsigned int green = SkColorGetG(color);
     unsigned int blue = SkColorGetB(color);
-    if (alpha) {
+    // Don't expose default value of pure white.
+    if (alpha && (red != 255 || green != 255 || blue != 255)) {
       base::string16 color_value = L"rgb(" + base::UintToString16(red) + L',' +
                                    base::UintToString16(green) + L',' +
                                    base::UintToString16(blue) + L')';
@@ -1946,11 +1947,14 @@ std::vector<base::string16> BrowserAccessibilityComWin::ComputeTextAttributes()
     unsigned int red = SkColorGetR(color);
     unsigned int green = SkColorGetG(color);
     unsigned int blue = SkColorGetB(color);
-    base::string16 color_value = L"rgb(" + base::UintToString16(red) + L',' +
-                                 base::UintToString16(green) + L',' +
-                                 base::UintToString16(blue) + L')';
-    SanitizeStringAttributeForIA2(color_value, &color_value);
-    attributes.push_back(L"color:" + color_value);
+    // Don't expose default value of black.
+    if (red || green || blue) {
+      base::string16 color_value = L"rgb(" + base::UintToString16(red) + L',' +
+                                   base::UintToString16(green) + L',' +
+                                   base::UintToString16(blue) + L')';
+      SanitizeStringAttributeForIA2(color_value, &color_value);
+      attributes.push_back(L"color:" + color_value);
+    }
   }
 
   base::string16 font_family(owner()->GetInheritedString16Attribute(
@@ -2043,8 +2047,8 @@ std::vector<base::string16> BrowserAccessibilityComWin::ComputeTextAttributes()
 
   base::string16 language(owner()->GetInheritedString16Attribute(
       ax::mojom::StringAttribute::kLanguage));
-  // Default value should be L"en-US".
-  if (!language.empty()) {
+  // Don't expose default value should of L"en-US".
+  if (!language.empty() && language != L"en-US") {
     SanitizeStringAttributeForIA2(language, &language);
     attributes.push_back(L"language:" + language);
   }

content/test/data/accessibility/css/color-expected-win.txt

-ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE offset:0 background-color:rgb(0\,0\,255) color:rgb(255\,0\,0) offset:1 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) ia2_hypertext='<obj0><obj1>'
+ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE offset:0 background-color:rgb(0\,0\,255) color:rgb(255\,0\,0) offset:1 ia2_hypertext='<obj0><obj1>'
 ++IA2_ROLE_PARAGRAPH offset:0 background-color:rgb(0\,0\,255) color:rgb(255\,0\,0) ia2_hypertext='Red on blue.'
 ++++ROLE_SYSTEM_STATICTEXT name='Red on blue.' offset:0 background-color:rgb(0\,0\,255) color:rgb(255\,0\,0) ia2_hypertext='Red on blue.'
-++IA2_ROLE_SECTION FOCUSABLE IA2_STATE_MULTI_LINE offset:0 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) offset:9 background-color:rgb(0\,0\,255) color:rgb(0\,0\,0) offset:25 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) offset:26 background-color:rgb(255\,255\,255) color:rgb(0\,255\,0) ia2_hypertext='Default. Blue background. Green text.'
-++++ROLE_SYSTEM_STATICTEXT name='Default.' offset:0 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) ia2_hypertext='Default.'
-++++ROLE_SYSTEM_STATICTEXT name=' ' offset:0 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) ia2_hypertext=' '
-++++ROLE_SYSTEM_STATICTEXT name='Blue background.' offset:0 background-color:rgb(0\,0\,255) color:rgb(0\,0\,0) ia2_hypertext='Blue background.'
-++++ROLE_SYSTEM_STATICTEXT name=' ' offset:0 background-color:rgb(255\,255\,255) color:rgb(0\,0\,0) ia2_hypertext=' '
-++++ROLE_SYSTEM_STATICTEXT name='Green text.' offset:0 background-color:rgb(255\,255\,255) color:rgb(0\,255\,0) ia2_hypertext='Green text.'
\ No newline at end of file
+++IA2_ROLE_SECTION FOCUSABLE IA2_STATE_MULTI_LINE offset:0 offset:9 background-color:rgb(0\,0\,255) offset:25 offset:26 color:rgb(0\,255\,0) ia2_hypertext='Default. Blue background. Green text.'
+++++ROLE_SYSTEM_STATICTEXT name='Default.' offset:0 ia2_hypertext='Default.'
+++++ROLE_SYSTEM_STATICTEXT name=' ' offset:0 ia2_hypertext=' '
+++++ROLE_SYSTEM_STATICTEXT name='Blue background.' offset:0 background-color:rgb(0\,0\,255) ia2_hypertext='Blue background.'
+++++ROLE_SYSTEM_STATICTEXT name=' ' offset:0 ia2_hypertext=' '
+++++ROLE_SYSTEM_STATICTEXT name='Green text.' offset:0 color:rgb(0\,255\,0) ia2_hypertext='Green text.'
\ No newline at end of file