Necessary for Daydream home integration.

UI mocks and assets are needed. So assign to Josh first.

Issue 713371 has been merged into this issue.

This will not be smooth until  issue 726590  is addressed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2efa616e207873fdbbf1ae8f144d16708b4a0d62

commit 2efa616e207873fdbbf1ae8f144d16708b4a0d62
Author: ymalik <ymalik@chromium.org>
Date: Mon Jun 26 16:40:13 2017

Show splash screen when entering VR from a deep-link

This CL adds the necessary splash screen ui to show when we are going to auto-present
WebVR content. The flow of things is that when we get a new auto-present intent, we enter
VR (not in web vr mode) and create VrShell with "web_vr_autopresentation_expected"
parameter. This tells UiSceneManager to show the splash screen. When the WebVR page
calles requestPresent, we enter WebVR mode and the ui scene manager hides the splash
screen.

Notes
- Currently, the UI not show up if Chrome is started for the first time. This has to do with the
  fact that we can't enter VR early in that case. bshe@ is working on that.
- The loading spinner on the splash screen is not added in this patch
- This patch expects a sane WebVR page in that it doesn't handle error cases such as
requestPresent never being called.

BUG= 699815 

Review-Url: https://codereview.chromium.org/2955483003
Cr-Commit-Position: refs/heads/master@{#482295}

[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/BUILD.gn
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/color_scheme.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/color_scheme.h
[add] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/textures/splash_screen_icon_texture.cc
[add] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/textures/splash_screen_icon_texture.h
[add] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_elements/splash_screen_icon.cc
[add] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_elements/splash_screen_icon.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_elements/ui_element_debug_id.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_interface.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_scene.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_scene.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_scene_manager.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_scene_manager.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/ui_scene_manager_unittest.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/vr_gl_thread.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/vr_gl_thread.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/vr_shell.cc
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/vr_shell.h
[modify] https://crrev.com/2efa616e207873fdbbf1ae8f144d16708b4a0d62/chrome/browser/android/vr_shell/vr_shell_gl.cc