Switch AccessibilityMode to be a bitmap

content/common/view_message_enums.h

Index: content/common/view_message_enums.h
diff --git a/content/common/view_message_enums.h b/content/common/view_message_enums.h
index 59a6da11b0aed6f04f35803b5ecde6422763356d..7d78075c663f1c3eb93956261c12b1ffec2d18ec 100644
--- a/content/common/view_message_enums.h
+++ b/content/common/view_message_enums.h
@@ -53,19 +53,32 @@ struct ViewMsg_Navigate_Type {
   };
 };
 
-enum AccessibilityMode {
-  // WebKit accessibility is off and no accessibility information is
-  // sent from the renderer to the browser process.
-  AccessibilityModeOff,
+enum AccessibilityModeFlag {
+  // Blink accessibility is on and accessibility information is sent from the
+  // renderer to the browser process. Note that none of the other flags do
+  // anything if this flag is off.
+  AccessibilityModeFlagRenderer = 1 << 0,
+
+  // Accessibility updates are processed to create platform trees and events are
+  // passed to platform APIs in the browser.
+  AccessibilityModeFlagPlatform = 1 << 1,
 
   // WebKit accessibility is on, but only limited information about

[David Tseng, 2014/01/27 22:16:06]

Blink

[aboxhall, 2014/01/28 00:18:42]

Done.

   // editable text nodes is sent to the browser process. Useful for

[David Tseng, 2014/01/27 22:16:06]

s/is/are

[aboxhall, 2014/01/28 00:18:42]

Nope :)
limited information (about editable text nodes) is sent...

[David Tseng, 2014/01/28 00:48:45]

Oops; yep. Never liked passive voice I guess.

[aboxhall, 2014/01/28 17:48:26]

Yeah, it's not the most elegant.

   // implementing limited UIA on tablets.
-  AccessibilityModeEditableTextOnly,
+  AccessibilityModeFlagEditableTextOnly = 1 << 2,
+};
 
-  // WebKit accessibility is on, and the full accessibility tree is synced
-  // to the browser process. Useful for screen readers and magnifiers.
+enum AccessibilityModeConstants {
+  // All accessibility is off.
+  AccessibilityModeOff = 0,
+
+  // Renderer accessibility is on, and platform APIs are called.
   AccessibilityModeComplete,
+
+  // Renderer accessibility is on, platform APIs are called, but only limited
+  // information is available (see AccessibilityModeFlagEditableTextOnly).
+  AccessibilityModeEditableTextOnly

[David Tseng, 2014/01/27 22:16:06]

Why can't we just include these in the above enum? i.e. complete is just 1<<0 |
1<<1

[aboxhall, 2014/01/28 00:18:42]

Huh, the constant values didn't make it in.

I'd rather not mix up the two concepts (flags and constants).

[David Tseng, 2014/01/28 00:48:45]

I'm not sure I see the distinction. They're all modes right? Some modes are just
composites of other modes.
There's also some inconsistent usage of the constants vs the flags; could be
kind of confusing.

[aboxhall, 2014/01/28 17:48:26]

Well, I don't think of the flags as modes, rather as components of modes. We
shouldn't ever be using a flag in isolation as a mode, except as a shortcut to
setting a mode with only that one flag set (which we pretty much never want to
do anyway).

[David Tseng, 2014/01/29 17:59:54]

Ok; so, it sounds like we should just keep the integer bit mask hidden from all
public API's right? So, SetAccessibilityMode should just take one of the
constant values.

 };
 
 #endif  // CONTENT_COMMON_VIEW_MESSAGES_ENUMS_H_