Browser Plugin: Don't crash browser when reloading crashed webview

We were accessing a NULL RWHV on BrowserPluginGuest::SetFocus. This CL
adds a guard to ensure we only attempt to set focus if we have a View.

BUG=413874

Review URL: https://codereview.chromium.org/564153003

Cr-Commit-Position: refs/heads/master@{#294674}

chrome/browser/apps/web_view_browsertest.cc

@@ -1193,7 +1193,11 @@ IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestLoadAbortNonWebSafeScheme) {
 }
 
 IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestReload) {
-  TestHelper("testReload", "web_view/shim", NEEDS_TEST_SERVER);
+  TestHelper("testReload", "web_view/shim", NO_TEST_SERVER);
+}
+
+IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestReloadAfterTerminate) {
+  TestHelper("testReloadAfterTerminate", "web_view/shim", NO_TEST_SERVER);
 }
 
 IN_PROC_BROWSER_TEST_F(WebViewTest, Shim_TestGetProcessId) {

chrome/test/data/extensions/platform_apps/web_view/shim/main.js

@@ -1367,6 +1367,40 @@ function testReload() {
   document.body.appendChild(webview);
 }
 
+// This test verifies that the reload method on webview functions as expected.
+function testReloadAfterTerminate() {
+  var triggerNavUrl = 'data:text/html,trigger navigation';
+  var webview = document.createElement('webview');
+
+  var step = 1;
+  webview.addEventListener('loadstop', function(e) {
+    switch (step) {
+      case 1:
+        webview.terminate();
+        break;
+      case 2:
+        setTimeout(function() { embedder.test.succeed(); }, 0);
+        break;
+      default:
+        window.console.log('Unexpected loadstop event, step = ' + step);
+        embedder.test.fail();
+        break;
+    }
+    ++step;
+  });
+
+  webview.addEventListener('exit', function(e) {
+    // Trigger a focus state change of the guest to test for
+    // http://crbug.com/413874.
+    webview.blur();
+    webview.focus();
+    setTimeout(function() { webview.reload(); }, 0);
+  });
+
+  webview.src = triggerNavUrl;
+  document.body.appendChild(webview);
+}
+
 // This test verifies that a <webview> is torn down gracefully when removed from
 // the DOM on exit.
 
@@ -1834,6 +1868,7 @@ embedder.test.testList = {
   'testNavigateAfterResize': testNavigateAfterResize,
   'testNavigationToExternalProtocol': testNavigationToExternalProtocol,
   'testReload': testReload,
+  'testReloadAfterTerminate': testReloadAfterTerminate,
   'testRemoveWebviewOnExit': testRemoveWebviewOnExit,
   'testRemoveWebviewAfterNavigation': testRemoveWebviewAfterNavigation,
   'testResizeWebviewResizesContent': testResizeWebviewResizesContent,

content/browser/browser_plugin/browser_plugin_guest.cc

@@ -109,13 +109,16 @@ base::WeakPtr<BrowserPluginGuest> BrowserPluginGuest::AsWeakPtr() {
 
 void BrowserPluginGuest::SetFocus(RenderWidgetHost* rwh, bool focused) {
   focused_ = focused;
+  if (!rwh)
+    return;
+
   rwh->Send(new InputMsg_SetFocus(rwh->GetRoutingID(), focused));
   if (!focused && mouse_locked_)
     OnUnlockMouse();
 
   // Restore the last seen state of text input to the view.
   RenderWidgetHostViewBase* rwhv = static_cast<RenderWidgetHostViewBase*>(
-      web_contents()->GetRenderWidgetHostView());
+      rwh->GetView());
   if (rwhv) {
     ViewHostMsg_TextInputState_Params params;
     params.type = last_text_input_type_;
@@ -718,9 +721,8 @@ void BrowserPluginGuest::OnResizeGuest(
 
 void BrowserPluginGuest::OnSetFocus(int browser_plugin_instance_id,
                                     bool focused) {
-
-  RenderWidgetHost* rwh = web_contents()->GetRenderWidgetHostView()->
-      GetRenderWidgetHost();
+  RenderWidgetHostView* rwhv = web_contents()->GetRenderWidgetHostView();
+  RenderWidgetHost* rwh = rwhv ? rwhv->GetRenderWidgetHost() : NULL;
   SetFocus(rwh, focused);
 }