Revert of Refactor Select-to-speak so that mouse events are forwarded to the extension.

Revert of Refactor Select-to-speak so that mouse events are forwarded to the extension. (patchset #7 id:120001 of https://codereview.chromium.org/2814213002/ )

Reason for revert:
FindIT detected it as culprit of test failures.
https://findit-for-me.appspot.com/waterfall/build-failure?url=https://build.chromium.org/p/chromium.memory/builders/Linux%20ChromiumOS%20MSan%20Tests/builds/561

Original issue's description:
> Refactor Select-to-speak so that mouse events are forwarded to the extension.
> 
> Previously the Select-to-speak event handler captured mouse events and
> turned them into accessibility events that could be caught by
> select-to-speak.
> 
> Instead, the event handler can mouse and keyboard events to the extension
> background page, and the extension can use the automation API to do a hit test.
> 
> This is mostly a refactoring change, but it gives us some more flexibility
> and makes the event handler simpler, possibly something that could be
> general-purpose, while putting more of the logic into the extension code.
> 
> BUG=699617
> CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation
> 
> Review-Url: https://codereview.chromium.org/2814213002
> Cr-Commit-Position: refs/heads/master@{#472339}
> Committed: https://chromium.googlesource.com/chromium/src/+/ccb40f537fbbc17772e7255a7b575661ce4353cd

TBR=dtseng@chromium.org,dmazzoni@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=699617

[kolos1, 2017-05-17 10:02:12]

The CQ bit was checked by kolos@chromium.org

[kolos1, 2017-05-17 10:02:13]

Created Revert of Refactor Select-to-speak so that mouse events are forwarded to
the extension.

[commit-bot: I haz the power, 2017-05-17 10:02:38]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-17 10:02:59]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-05-17 10:03:01]

Failed to apply patch for chrome/browser/chromeos/BUILD.gn:
While running git apply --index -3 -p1;
  error: patch failed: chrome/browser/chromeos/BUILD.gn:125
  error: repository lacks the necessary blob to fall back on 3-way merge.
  error: chrome/browser/chromeos/BUILD.gn: patch does not apply

Patch:       chrome/browser/chromeos/BUILD.gn
Index: chrome/browser/chromeos/BUILD.gn
diff --git a/chrome/browser/chromeos/BUILD.gn b/chrome/browser/chromeos/BUILD.gn
index
6dcd4ed98d0dbe8d818adfd7d24e03951b9c7675..102c6781c895cbb575ce2124449086b722ac8e82
100644
--- a/chrome/browser/chromeos/BUILD.gn
+++ b/chrome/browser/chromeos/BUILD.gn
@@ -125,7 +125,6 @@
     "//ui/display",
     "//ui/display/manager",
     "//ui/events:dom_keycode_converter",
-    "//ui/events/blink",
     "//ui/events/devices",
     "//ui/events/platform",
     "//ui/file_manager",