Navigation transitions: Exposed "setBackgroundOpaque" to ContentViewCore

The navigation transition needs the transition page to render transparently over top the current tab, so we need to expose this call to java.

Design doc: https://docs.google.com/a/chromium.org/document/d/17jg1RRL3RI969cLwbKBIcoGDsPwqaEdBxafGNYGwiY4/edit# 
Implementation details: https://docs.google.com/a/chromium.org/document/d/1kREPtFJaeLoDKwrfmrYTD7DHCdxX1RzFBga2gNY8lyE/edit#heading=h.bng2kpmyvxq5
BUG=370696

Review URL: https://codereview.chromium.org/284413007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274587 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/android/content_view_core_impl.cc

@@ -1594,6 +1594,12 @@ jint ContentViewCoreImpl::GetCurrentRenderProcessId(JNIEnv* env, jobject obj) {
       web_contents_->GetRenderViewHost());
 }
 
+void ContentViewCoreImpl::SetBackgroundOpaque(JNIEnv* env, jobject jobj,
+    jboolean opaque) {
+  if (GetRenderWidgetHostViewAndroid())
+    GetRenderWidgetHostViewAndroid()->SetBackgroundOpaque(opaque);
+}
+
 void ContentViewCoreImpl::OnSmartClipDataExtracted(
     const base::string16& result) {
   JNIEnv* env = AttachCurrentThread();

content/browser/android/content_view_core_impl.h

@@ -220,6 +220,8 @@ class ContentViewCoreImpl : public ContentViewCore,
                             jint width,
                             jint height);
 
+  void SetBackgroundOpaque(JNIEnv* env, jobject jobj, jboolean opaque);
+
   jint GetCurrentRenderProcessId(JNIEnv* env, jobject obj);
 
   // --------------------------------------------------------------------------

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

@@ -3020,6 +3020,12 @@ public class ContentViewCore
         mSmartClipDataListener = listener;
     }
 
+    public void setBackgroundOpaque(boolean opaque) {
+        if (mNativeContentViewCore != 0) {
+            nativeSetBackgroundOpaque(mNativeContentViewCore, opaque);
+        }
+    }
+
     /**
      * Offer a long press gesture to the embedding View, primarily for WebView compatibility.
      *
@@ -3230,4 +3236,5 @@ public class ContentViewCore
 
     private native void nativeExtractSmartClipData(long nativeContentViewCoreImpl,
             int x, int y, int w, int h);
+    private native void nativeSetBackgroundOpaque(long nativeContentViewCoreImpl, boolean opaque);
 }