Linking arm and arm64 gvr static shim library.

This should reduce our binary size increase significantly for VR
related feature, as well as avoid issue with crazy linker which has
problem handling two shared libraries.

Note that the static library is mostly a shim lib. It will dynamically
load the correct library from VrCore service at runtime when needed.
Our initial target is Pixel and Pixel XL phones. And VrCore should exist
in both phones. If VrCore doesn't exist or the version is older than we
expect, VR will be disabled. Support for x86 and x64 will be added later.

BUG=644785

Review-Url: https://codereview.chromium.org/2467873004
Cr-Original-Commit-Position: refs/heads/master@{#431699}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0907c2d02be6980427e4ecc372c47985e7dddffd

config/features.gni

@@ -81,12 +81,10 @@ declare_args() {
 
   # Enable WebVR support by default on Android
   # Still requires command line flag to access API
-  # TODO(bshe): Remove is_component_build once we can statically link gvr
-  # library. Currently gvr library only has a prebuild so file which causes
-  # linking issue for non component build.
+  # TODO(bshe): Enable for other architecture too. Currently we only support arm
+  # and arm64.
   enable_webvr = is_android && is_component_build &&
-                 (current_cpu == "x86" || current_cpu == "x64" ||
-                  current_cpu == "arm" || current_cpu == "arm64")
+                 (current_cpu == "arm" || current_cpu == "arm64")
 }
 
 # Additional dependent variables -----------------------------------------------