Enable key event injection in ChromeVox js e2e tests

- minimal setup for enabling and creating vk which routes key events
- add a test for native find
- eliminate double speak in find handler by checking current range

Bug: 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I13000974b3fe917c4179191b72d8940551612fbb
Reviewed-on: https://chromium-review.googlesource.com/827166
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524570}

chrome/browser/resources/chromeos/chromevox/cvox2/background/background_test.extjs

@@ -24,6 +24,8 @@ BackgroundTest.prototype = {
   setUp: function() {
     window.RoleType = chrome.automation.RoleType;
     window.doCmd = this.doCmd;
+    window.press = this.press;
+    window.Mod = constants.ModifierFlag;
 
     this.forceContextualLastOutput();
   },
@@ -49,6 +51,12 @@ BackgroundTest.prototype = {
     };
   },
 
+  press: function(keyCode, keyName, modifiers) {
+    return function() {
+      BackgroundKeyboardHandler.sendKeyPress(keyCode, keyName, modifiers);
+    };
+  },
+
   linksAndHeadingsDoc: function() {/*!
     <p>start</p>
     <a href='#a'>alpha</a>
@@ -1272,3 +1280,20 @@ TEST_F('BackgroundTest', 'NodeVsSubnode', function() {
         .replay();
   });
 });
+
+TEST_F('BackgroundTest', 'NativeFind', function() {
+  var mockFeedback = this.createMockFeedback();
+  this.runWithLoadedTree(function(root) {/*!
+    <a href="#">grape</a>
+    <a href="#">pineapple</a>
+  */}, function(root) {
+    mockFeedback.call(press(70, 'F', Mod.CONTROL))
+        .expectSpeech('Find', 'Edit text')
+        .call(press(71, 'G'))
+        .expectSpeech('grape', 'Link')
+        .call(press(8, 'Backspace'))
+        .call(press(76, 'L'))
+        .expectSpeech('pineapple', 'Link')
+        .replay();
+  });
+});

chrome/browser/resources/chromeos/chromevox/testing/chromevox_e2e_test_base.js

@@ -34,16 +34,20 @@ ChromeVoxE2ETest.prototype = {
   testGenCppIncludes: function() {
     GEN_BLOCK(function() { /*!
 #include "ash/accessibility/accessibility_delegate.h"
+#include "ash/shell.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
 #include "chrome/common/extensions/extension_constants.h"
+#include "ui/keyboard/keyboard_util.h"
     */ });
   },
 
   /** @override */
   testGenPreamble: function() {
     GEN_BLOCK(function() { /*!
+  keyboard::SetRequestedKeyboardState(keyboard::KEYBOARD_STATE_ENABLED);
+  ash::Shell::Get()->CreateKeyboard();
   base::Closure load_cb =
       base::Bind(&chromeos::AccessibilityManager::EnableSpokenFeedback,
           base::Unretained(chromeos::AccessibilityManager::Get()),