Expose images to accessibility

Blink has some loose heuristics to ignore images, even ones that are important for interaction.

Specifically, web authors do use horizontal images (i.e. 1d images) to convey information to screen readers that is not purely presentational.

At the very least, it should be up to each client to make an intelligent determination.

This cl also adds missing graphics predicates and key bindings to ChromeVox.

BUG=641848
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2479593007
Cr-Commit-Position: refs/heads/master@{#430199}

chrome/browser/resources/chromeos/chromevox/chromevox/background/keymaps/next_keymap.json

@@ -173,6 +173,25 @@
         }
       }
     },
+    {
+      "command": "previousGraphic",
+      "sequence": {
+        "cvoxModifier": true,
+        "keys": {
+          "keyCode": [71],
+          "shiftKey": [true]
+        }
+      }
+    },
+    {
+      "command": "nextGraphic",
+      "sequence": {
+        "cvoxModifier": true,
+        "keys": {
+          "keyCode": [71]
+        }
+      }
+    },
     {
       "command": "nextHeading",
       "sequence": {

chrome/browser/resources/chromeos/chromevox/cvox2/background/automation_predicate.js

@@ -124,6 +124,14 @@ AutomationPredicate.control = AutomationPredicate.match({
   ]
 });
 
+/**
+ * @param {!AutomationNode} node
+ * @return {boolean}
+ */
+AutomationPredicate.image = function(node) {
+  return node.role == Role.image && !!(node.name || node.url);
+};
+
 /** @type {AutomationPredicate.Unary} */
 AutomationPredicate.linkOrControl = AutomationPredicate.match({
   anyPredicate: [

chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js

@@ -276,6 +276,16 @@ CommandHandler.onCommand = function(command) {
       pred = AutomationPredicate.formField;
       predErrorMsg = 'no_previous_form_field';
       break;
+    case 'previousGraphic':
+      dir = Dir.BACKWARD;
+      pred = AutomationPredicate.image;
+      predErrorMsg = 'no_previous_graphic';
+      break;
+    case 'nextGraphic':
+      dir = Dir.FORWARD;
+      pred = AutomationPredicate.image;
+      predErrorMsg = 'no_next_graphic';
+      break;
     case 'nextHeading':
       dir = Dir.FORWARD;
       pred = AutomationPredicate.heading;

chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js

@@ -446,6 +446,10 @@ Output.RULES = {
           '$nameOrDescendants= ' +
           '$if($hierarchicalLevel, @tag_h+$hierarchicalLevel, $role) $state'
     },
+    image: {
+      speak: '$if($name, $name, $urlFilename) ' +
+          '$value $state $role $description',
+    },
     inlineTextBox: {
       speak: '$name='
     },
@@ -1073,6 +1077,19 @@ Output.prototype = {
           if (earcon)
             options.annotation.push(earcon);
           this.append_(buff, node.name, options);
+        } else if (token == 'urlFilename') {
+          options.annotation.push('name');
+          var url = node.url;
+          var filename = '';
+          if (url.substring(0, 4) != 'data') {
+            filename =
+                url.substring(url.lastIndexOf('/') + 1, url.lastIndexOf('.'));
+
+            // Hack to not speak the filename if it's ridiculously long.
+            if (filename.length >= 30)
+            filename = filename.substring(0, 16) + '...';
+          }
+          this.append_(buff, filename, options);
         } else if (token == 'nameFromNode') {
           if (chrome.automation.NameFromType[node.nameFrom] ==
               'contents')

content/test/data/accessibility/html/img-empty-alt-expected-blink.txt

@@ -4,5 +4,6 @@ rootWebArea
 ++++++staticText name='unread '
 ++++++++inlineTextBox name='unread '
 ++++link name='read'
+++++++image
 ++++++staticText name='read'
 ++++++++inlineTextBox name='read'

content/test/data/accessibility/html/img-empty-alt-expected-mac.txt

@@ -3,4 +3,5 @@ AXWebArea
 ++++AXLink AXTitle='unread '
 ++++++AXStaticText AXValue='unread '
 ++++AXLink AXTitle='read'
+++++++AXImage AXDescription='/read.jpg'
 ++++++AXStaticText AXValue='read'

content/test/data/accessibility/html/img-expected-android.txt

 android.webkit.WebView focusable focused scrollable
 ++android.view.View
-++++android.widget.Image role_description='graphic' name='pipe'
+++++android.widget.Image role_description='graphic' name='pipe'
\ No newline at end of file
+++++android.widget.Image role_description='graphic' name='pipe'
+++++android.widget.Image role_description='graphic' name='  '

content/test/data/accessibility/html/img-expected-mac.txt

 AXWebArea
 ++AXGroup
 ++++AXImage AXRoleDescription='image' AXDescription='pipe'
+++++AXImage AXRoleDescription='image' AXDescription='/pipe.jpg'
+++++AXImage AXRoleDescription='image' AXDescription='  '

content/test/data/accessibility/html/img-expected-win.txt

 ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE
 ++IA2_ROLE_SECTION
 ++++ROLE_SYSTEM_GRAPHIC name='pipe' READONLY xml-roles:img
+++++ROLE_SYSTEM_GRAPHIC READONLY xml-roles:img
+++++ROLE_SYSTEM_GRAPHIC name='  ' READONLY xml-roles:img

third_party/WebKit/LayoutTests/accessibility/img-alt-tag-only-whitespace-expected.txt

@@ -2,12 +2,12 @@ CONSOLE MESSAGE: line 26: Image description:  Image
 
 
 
-This tests that images with alt tags that only have white space are ignored.
+This tests that images with alt tags that only have white space are not ignored.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
-PASS imagesGroup.childrenCount is 4
+PASS imagesGroup.childrenCount is 6
 PASS successfullyParsed is true
 
 TEST COMPLETE

third_party/WebKit/LayoutTests/accessibility/img-alt-tag-only-whitespace.html

@@ -16,14 +16,14 @@
 
 <script>
 
-    description("This tests that images with alt tags that only have white space are ignored.");
+    description("This tests that images with alt tags that only have white space are not ignored.");
 
     if (window.accessibilityController) {
 
         document.getElementById("images").focus();
         var imagesGroup = accessibilityController.focusedElement;
-        shouldBe("imagesGroup.childrenCount", "4");
-        console.log("Image description: " + imagesGroup.childAtIndex(2).name);
+        shouldBe("imagesGroup.childrenCount", "6");
+        console.log("Image description: " + imagesGroup.childAtIndex(4).name);
     }
 
 </script>

third_party/WebKit/LayoutTests/accessibility/img-fallsback-to-title-expected.txt

-    
+  
 test
 test
 This tests that images will fallback to using the title attribute if no other descriptive text is present.
@@ -18,7 +18,6 @@ Image3 description:
 Image4 name: test4
 Image4 description: 
 
-PASS accessibilityController.accessibleElementById('img-ignored') is undefined
 PASS successfullyParsed is true
 
 TEST COMPLETE

third_party/WebKit/LayoutTests/accessibility/img-fallsback-to-title.html

@@ -5,7 +5,6 @@
 </head>
 <body id="body">
 
-    <img id="img-ignored" alt="" height="100" width="100">
     <img id="img1" title="test1" height="100" width="100">
     <img id="img2" alt="alt" title="test2" height="100" width="100">
     <div id="img3" role="img" title="test3" width="100" height="100">test</div>
@@ -41,9 +40,6 @@
         var image4 = accessibilityController.accessibleElementById("img4");
         debug("Image4 name: " + image4.name);
         debug("Image4 description: " + image4.description + "<br>");
-
-        // Verify that the first image (with an empty alt tag) is ignored
-        shouldBe("accessibilityController.accessibleElementById('img-ignored')", "undefined");
     }
 
 </script>

third_party/WebKit/LayoutTests/inspector-protocol/accessibility/accessibility-ignoredNodes-expected.txt

@@ -247,20 +247,43 @@ Content within label refers to label container
     "nodes": [
       {
         "nodeId": "<string>",
-        "ignored": true,
-        "ignoredReasons": [
-          {
-            "name": "emptyAlt",
-            "value": {
-              "type": "boolean",
-              "value": true
-            }
-          }
-        ],
+        "ignored": false,
         "role": {
           "type": "role",
           "value": "img"
-        }
+        },
+        "name": {
+          "type": "computedString",
+          "value": "",
+          "sources": [
+            {
+              "type": "relatedElement",
+              "attribute": "aria-labelledby"
+            },
+            {
+              "type": "attribute",
+              "attribute": "aria-label"
+            },
+            {
+              "type": "attribute",
+              "value": {
+                "type": "computedString",
+                "value": ""
+              },
+              "attribute": "alt",
+              "attributeValue": {
+                "type": "string",
+                "value": ""
+              }
+            },
+            {
+              "type": "attribute",
+              "attribute": "title",
+              "superseded": true
+            }
+          ]
+        },
+        "properties": []
       }
     ]
   }

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp

@@ -697,52 +697,8 @@ bool AXLayoutObject::computeAccessibilityIsIgnored(
     return true;
   }
 
-  // ignore images seemingly used as spacers
-  if (isImage()) {
-    // If the image can take focus, it should not be ignored, lest the user not
-    // be able to interact with something important.
-    if (canSetFocusAttribute())
-      return false;
-
-    if (node && node->isElementNode()) {
-      Element* elt = toElement(node);
-      const AtomicString& alt = elt->getAttribute(altAttr);
-      // don't ignore an image that has an alt tag
-      if (!alt.getString().containsOnlyWhitespace())
-        return false;
-      // informal standard is to ignore images with zero-length alt strings
-      if (!alt.isNull()) {
-        if (ignoredReasons)
-          ignoredReasons->append(IgnoredReason(AXEmptyAlt));
-        return true;
-      }
-    }
-
-    if (isNativeImage() && m_layoutObject->isImage()) {
-      // check for one-dimensional image
-      LayoutImage* image = toLayoutImage(m_layoutObject);
-      if (image->size().height() <= 1 || image->size().width() <= 1) {
-        if (ignoredReasons)
-          ignoredReasons->append(IgnoredReason(AXProbablyPresentational));
-        return true;
-      }
-
-      // Check whether laid out image was stretched from one-dimensional file
-      // image.
-      if (image->cachedImage()) {
-        LayoutSize imageSize = image->cachedImage()->imageSize(
-            LayoutObject::shouldRespectImageOrientation(m_layoutObject),
-            image->view()->zoomFactor());
-        if (imageSize.height() <= 1 || imageSize.width() <= 1) {
-          if (ignoredReasons)
-            ignoredReasons->append(IgnoredReason(AXProbablyPresentational));
-          return true;
-        }
-        return false;
-      }
-    }
+  if (isImage())
     return false;
-  }
 
   if (isCanvas()) {
     if (canvasHasFallbackContent())