Scope and clean up uses of AccessibilityMode.

content/common/accessibility_mode.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_COMMON_ACCESSIBILITY_MODE_ENUMS_H_
+#define CONTENT_COMMON_ACCESSIBILITY_MODE_ENUMS_H_
+
+namespace content {
+
+class AccessibilityMode {
+ public:
+  static constexpr int kOff = 0;
+
+  // Native accessibility APIs, specific to each platform, are enabled.
+  // When this mode is set that indicates the presence of a third-party
+  // client accessing Chrome via accessibility APIs. However, unless one
+  // of the modes below is set, the contents of web pages will not be
+  // accessible.
+  static constexpr int kNativeAPIs = 1 << 0;
+
+  // The renderer process will generate an accessibility tree containing
+  // basic information about all nodes, including role, name, value,
+  // state, and location. This is the minimum mode required in order for
+  // web contents to be accessible, and the remaining modes are meaningless
+  // unless this one is set.
+  //
+  // Note that sometimes this mode will be set when kNativeAPI is not, when the
+  // content layer embedder is providing accessibility support via some other
+  // mechanism other than what's implemented in content/browser.
+  static constexpr int kWebContents = 1 << 1;
+
+  // The accessibility tree will contain inline text boxes, which are
+  // necessary to expose information about line breaks and word boundaries.
+  // Without this mode, you can retrieve the plaintext value of a text field
+  // but not the information about how it's broken down into lines.
+  //
+  // Note that when this mode is off it's still possible to request inline
+  // text boxes for a specific node on-demand, asynchronously.
+  static constexpr int kInlineTextBoxes = 1 << 2;
+
+  // The accessibility tree will contain extra accessibility
+  // attributes typically only needed by screen readers and other
+  // assistive technology for blind users. Examples include text style
+  // attributes, table cell information, live region properties, range
+  // values, and relationship attributes.
+  static constexpr int kScreenReader = 1 << 3;
+
+  // The accessibility tree will contain the HTML tag name and HTML attributes
+  // for all accessibility nodes that come from web content.
+  static constexpr int kHTML = 1 << 4;
+
+  static constexpr int kComplete =

[dmazzoni, 2017/02/23 17:08:21]

I would have made kComplete and kWebContentsOnly into
full AccessibilityModes rather than just additional constants.

Something like:

(outside of class)

const AccessibilityMode kAccessibilityModeComplete =
    AccessibilityMode(AccessibilityMode::kNativeAPIs |
                      ...);

That way you can pass it directly into a function that
expects an accessibility mode rather than always needing to
create one.

Same with kAccessibilityModeNone.

To put it another way: the constants inside the class are
*mode flags*, these constants are *modes*.

[dougt, 2017/02/27 03:12:57]

After discussion, we decided to try to remove the complex classes from this
header and define them where needed.  This also means we're going to be very
explict/verbose about what flags we use.

+      kNativeAPIs | kWebContents | kInlineTextBoxes | kScreenReader | kHTML;
+
+  static constexpr int kWebContentsOnly =
+      kWebContents | kInlineTextBoxes | kScreenReader | kHTML;
+
+  AccessibilityMode() : flags_(0) {}
+  AccessibilityMode(int flag) : flags_(flag) {}

[dmazzoni, 2017/02/23 17:08:21]

nit: flag -> flags

[danakj, 2017/02/23 21:15:02]

explicit

[dougt, 2017/02/27 03:12:57]

Done.

+
+  bool hasMode(int flag) const { return (flags_ & flag) > 0; }

[dmazzoni, 2017/02/23 17:08:21]

No strong feelings either way, but I wonder if this should
be hasModeFlag?

The mode is all of the flags, each one is one mode flag.

[danakj, 2017/02/23 21:15:02]

+1. Also has_mode, not hasMode, is chromium style. Same throughout.

[dougt, 2017/02/27 03:12:57]

Then, we should also change setMode to setModeFlag?

+
+  void setMode(int flag, bool value) {
+    flags_ = value ? (flags_ | flag) : (flags_ & ~flag);
+  }
+
+  bool operator==(AccessibilityMode rhs) const {
+    if (flags_ == rhs.flags_)
+      return true;
+    return false;
+  }
+
+  bool operator!=(AccessibilityMode rhs) const { return !(*this == rhs); }
+
+  AccessibilityMode& operator|=(const AccessibilityMode& rhs) {
+    flags_ |= rhs.flags_;
+    return *this;
+  }
+
+  // Get internal value for serialization.
+  int get() const { return flags_; }
+
+ private:
+  int flags_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_ACCESSIBILITY_MODE_ENUMS_H_