Added experimental Share API on Android behind flag.

chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java

Index: chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java b/chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java
index 6fb722662f010ce79baaf2c82965c6e345ffb794..42a06cca06e12c7cc1a3d34b58c1fb9ff3bce0e4 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/mojo/ChromeInterfaceRegistrar.java
@@ -6,9 +6,11 @@ package org.chromium.chrome.browser.mojo;
 
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.chrome.browser.payments.PaymentRequestFactory;
+import org.chromium.chrome.browser.webshare.ShareServiceImplementationFactory;
 import org.chromium.content.browser.InterfaceRegistry;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.mojom.payments.PaymentRequest;
+import org.chromium.mojom.webshare.ShareService;
 
 /**
  * Registers interfaces exposed by Chrome in the given registry.
@@ -18,5 +20,7 @@ class ChromeInterfaceRegistrar {
     private static void exposeInterfacesToFrame(
             InterfaceRegistry registry, WebContents webContents) {
         registry.addInterface(PaymentRequest.MANAGER, new PaymentRequestFactory(webContents));
+        registry.addInterface(
+                ShareService.MANAGER, new ShareServiceImplementationFactory(webContents));
     }
 }