Add support for faster, more limited accessibility modes.

content/browser/accessibility/browser_accessibility_state_impl.cc

 // Copyright (c) 2012 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.
 
 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "build/build_config.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/content_switches.h"
 #include "ui/gfx/color_utils.h"
 
 namespace content {
 
+// IMPORTANT!
+// These values are written to logs.  Do not renumber or delete
+// existing items; add new entries to the end of the list.
+enum ModeFlagHistogramValue {
+  UMA_AX_MODE_FLAG_NATIVE_APIS = 0,
+  UMA_AX_MODE_FLAG_WEB_CONTENTS = 1,
+  UMA_AX_MODE_FLAG_INLINE_TEXT_BOXES = 2,
+  UMA_AX_MODE_FLAG_SCREEN_READER = 3,
+  UMA_AX_MODE_FLAG_HTML = 4,
+
+  // This must always be the last enum. It's okay for its value to
+  // increase, but none of the other enum values may change.
+  UMA_AX_MODE_FLAG_MAX
+};
+
+// Record a histograms for an accessibility mode when it's enabled.
+void RecordNewAccessibilityModeFlags(ModeFlagHistogramValue mode_flag) {
+  UMA_HISTOGRAM_ENUMERATION("Accessibility.ModeFlag",
+                            mode_flag,
+                            UMA_AX_MODE_FLAG_MAX);
+}
+
 // Update the accessibility histogram 45 seconds after initialization.
-static const int kAccessibilityHistogramDelaySecs = 45;
+static const int ACCESSIBILITY_HISTOGRAM_DELAY_SECS = 45;
 
 // static
 BrowserAccessibilityState* BrowserAccessibilityState::GetInstance() {
   return BrowserAccessibilityStateImpl::GetInstance();
 }
 
 // static
 BrowserAccessibilityStateImpl* BrowserAccessibilityStateImpl::GetInstance() {
   return base::Singleton<
       BrowserAccessibilityStateImpl,
@@ skipping 15 matching lines @@
   // thread.
   BrowserThread::ID update_histogram_thread = BrowserThread::UI;
 #endif
 
   // We need to AddRef() the leaky singleton so that Bind doesn't
   // delete it prematurely.
   AddRef();
   BrowserThread::PostDelayedTask(
       update_histogram_thread, FROM_HERE,
       base::Bind(&BrowserAccessibilityStateImpl::UpdateHistograms, this),
-      base::TimeDelta::FromSeconds(kAccessibilityHistogramDelaySecs));
+      base::TimeDelta::FromSeconds(ACCESSIBILITY_HISTOGRAM_DELAY_SECS));
 }
 
 BrowserAccessibilityStateImpl::~BrowserAccessibilityStateImpl() {
 }
 
 void BrowserAccessibilityStateImpl::OnScreenReaderDetected() {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableRendererAccessibility)) {
     return;
   }
@@ skipping 38 matching lines @@
 void BrowserAccessibilityStateImpl::UpdateHistogramsForTesting() {
   UpdateHistograms();
 }
 
 void BrowserAccessibilityStateImpl::UpdateHistograms() {
   UpdatePlatformSpecificHistograms();
 
   for (size_t i = 0; i < histogram_callbacks_.size(); ++i)
     histogram_callbacks_[i].Run();
 
   UMA_HISTOGRAM_BOOLEAN("Accessibility.State", IsAccessibleBrowser());

[Ilya Sherman, 2016/12/19 22:58:29]

Please add a TODO to remove this histogram, along with a target milestone.

[dmazzoni, 2016/12/19 23:02:15]

Done.

   UMA_HISTOGRAM_BOOLEAN("Accessibility.InvertedColors",
                         color_utils::IsInvertedColorScheme());
   UMA_HISTOGRAM_BOOLEAN("Accessibility.ManuallyEnabled",
                         base::CommandLine::ForCurrentProcess()->HasSwitch(
                             switches::kForceRendererAccessibility));
 }
 
 #if !defined(OS_WIN) && !defined(OS_MACOSX)
 void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
 }
 #endif
 
 void BrowserAccessibilityStateImpl::AddAccessibilityModeFlags(
     AccessibilityMode mode) {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableRendererAccessibility)) {
     return;
   }
 
+  AccessibilityMode previous_mode = accessibility_mode_;
   accessibility_mode_ |= mode;
+  if (accessibility_mode_ == previous_mode)
+    return;
+
+  // Retrieve only newly added modes for the purposes of logging.
+  AccessibilityMode new_mode_flags = accessibility_mode_ & (~previous_mode);
+  if (new_mode_flags & ACCESSIBILITY_MODE_FLAG_NATIVE_APIS)
+    RecordNewAccessibilityModeFlags(UMA_AX_MODE_FLAG_NATIVE_APIS);
+  if (new_mode_flags & ACCESSIBILITY_MODE_FLAG_WEB_CONTENTS)
+    RecordNewAccessibilityModeFlags(UMA_AX_MODE_FLAG_WEB_CONTENTS);
+  if (new_mode_flags & ACCESSIBILITY_MODE_FLAG_INLINE_TEXT_BOXES)
+    RecordNewAccessibilityModeFlags(UMA_AX_MODE_FLAG_INLINE_TEXT_BOXES);
+  if (new_mode_flags & ACCESSIBILITY_MODE_FLAG_SCREEN_READER)
+    RecordNewAccessibilityModeFlags(UMA_AX_MODE_FLAG_SCREEN_READER);
+  if (new_mode_flags & ACCESSIBILITY_MODE_FLAG_HTML)
+    RecordNewAccessibilityModeFlags(UMA_AX_MODE_FLAG_HTML);
+
   std::vector<WebContentsImpl*> web_contents_vector =
       WebContentsImpl::GetAllWebContents();
   for (size_t i = 0; i < web_contents_vector.size(); ++i)
     web_contents_vector[i]->AddAccessibilityMode(accessibility_mode_);
 }
 
 void BrowserAccessibilityStateImpl::RemoveAccessibilityModeFlags(
     AccessibilityMode mode) {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kForceRendererAccessibility) &&
       mode == ACCESSIBILITY_MODE_COMPLETE) {
     return;
   }
 
   accessibility_mode_ = accessibility_mode_ ^ (mode & accessibility_mode_);
   std::vector<WebContentsImpl*> web_contents_vector =
       WebContentsImpl::GetAllWebContents();
   for (size_t i = 0; i < web_contents_vector.size(); ++i)
     web_contents_vector[i]->SetAccessibilityMode(accessibility_mode());
 }
 
 }  // namespace content