VR: Dynamically load GVR Keyboard implementation

This CL add the necessary glue to wire up the keyboard API to its
implementation in the Daydream Keyboard APK.

The keyboard can be temporarily be summoned via the app button by
turning on the vr-browser-keyboard runtime flag. Follow-up CLs will
introduce the keyboard element and remove the temporary code in
VrShellGl.

Bug: 641470
Change-Id: I3d1372aa335db69c1e38adbb00a67993f9eea1e0
Reviewed-on: https://chromium-review.googlesource.com/731568
Commit-Queue: Yash Malik <[email protected]>
Reviewed-by: Yaron Friedman <[email protected]>
Reviewed-by: Biao She <[email protected]>
Reviewed-by: Amirhossein Simjour <[email protected]>
Reviewed-by: Max Moroz <[email protected]>
Reviewed-by: Ian Vollick <[email protected]>
Cr-Commit-Position: refs/heads/master@{#517638}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 1aeed0b1..ffd4559 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2176,6 +2176,9 @@
     {"vr-browsing", flag_descriptions::kVrBrowsingName,
      flag_descriptions::kVrBrowsingDescription, kOsAndroid,
      FEATURE_VALUE_TYPE(features::kVrBrowsing)},
+    {"vr-browser-keyboard", flag_descriptions::kVrBrowserKeyboardName,
+     flag_descriptions::kVrBrowserKeyboardDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(features::kVrBrowserKeyboard)},
     {"vr-browsing-experimental-features",
      flag_descriptions::kVrBrowsingExperimentalFeaturesName,
      flag_descriptions::kVrBrowsingExperimentalFeaturesDescription, kOsAndroid,