Adding option for Stop/Reload in location bar.

Currently reload/stop button is not present in content shell. If user
has to do reload operation then only option to do that is select
the url bar and click go button.Similarly stop button is not present. To stop loading of page only option is to press back button.
Added code to support stop/reload option.

BUG=

Review URL: https://codereview.chromium.org/513183002

Cr-Commit-Position: refs/heads/master@{#292778}

content/shell/android/java/res/layout/shell_view.xml

@@ -17,6 +17,16 @@
         android:layout_height="wrap_content"
         android:orientation="horizontal"
         android:background="@drawable/progress">
+        <ImageButton android:id="@+id/stop"
+            android:layout_width="38dp"
+            android:layout_height="38dp"
+            android:src="@android:drawable/ic_menu_close_clear_cancel"
+            android:scaleType="center" />
+        <ImageButton android:id="@+id/reload"
+            android:layout_width="38dp"
+            android:layout_height="38dp"
+            android:src="@drawable/ic_refresh"
+            android:scaleType="centerCrop" />
         <EditText android:id="@+id/url"
             android:layout_width="0dp"
             android:layout_height="wrap_content"

content/shell/android/java/src/org/chromium/content_shell/Shell.java

@@ -49,6 +49,8 @@ public class Shell extends LinearLayout {
     private EditText mUrlTextView;
     private ImageButton mPrevButton;
     private ImageButton mNextButton;
+    private ImageButton mStopButton;
+    private ImageButton mReloadButton;
 
     private ClipDrawable mProgressDrawable;
 
@@ -213,6 +215,20 @@ public class Shell extends LinearLayout {
                 if (mContentViewCore.canGoForward()) mContentViewCore.goForward();
             }
         });
+        mStopButton = (ImageButton)findViewById(R.id.stop);
+        mStopButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                if (mLoading) mContentViewCore.stopLoading();
+            }
+        });
+        mReloadButton = (ImageButton)findViewById(R.id.reload);
+        mReloadButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mContentViewCore.reload(true);
+            }
+        });
     }
 
     @SuppressWarnings("unused")
@@ -277,6 +293,10 @@ public class Shell extends LinearLayout {
     private void enableUiControl(int controlId, boolean enabled) {
         if (controlId == 0) mPrevButton.setEnabled(enabled);
         else if (controlId == 1) mNextButton.setEnabled(enabled);
+        else if (controlId == 2) {
+            mStopButton.setVisibility(enabled ? VISIBLE : GONE);
+            mReloadButton.setVisibility(enabled ? GONE : VISIBLE);
+        }
     }
 
     /**