Add setting to isolate zoom changes by default.

content/browser/web_contents/web_contents_impl_unittest.cc

Index: content/browser/web_contents/web_contents_impl_unittest.cc
diff --git a/content/browser/web_contents/web_contents_impl_unittest.cc b/content/browser/web_contents/web_contents_impl_unittest.cc
index 8ba2b0522f53ff633709f2e7f39b5d4d57133d65..f1685952b06ee88e70e0a8e111c542552341ebdf 100644
--- a/content/browser/web_contents/web_contents_impl_unittest.cc
+++ b/content/browser/web_contents/web_contents_impl_unittest.cc
@@ -53,6 +53,7 @@
 #include "content/test/test_web_contents.h"
 #include "net/test/cert_test_util.h"
 #include "net/test/test_data_directory.h"
+#include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "url/url_constants.h"
@@ -3446,4 +3447,28 @@ TEST_F(WebContentsImplTest, ResetJavaScriptDialogOnUserNavigate) {
   contents()->SetJavaScriptDialogManagerForTesting(nullptr);
 }
 
+namespace {
+
+class MockWebContentsObserver : public WebContentsObserver {
+ public:
+   explicit MockWebContentsObserver(WebContents* web_contents)
+     : WebContentsObserver(web_contents) {}
+   MOCK_METHOD2(
+       WebContentsReplaced,
+       void(WebContents* old_web_contents, WebContents* new_web_contents));
+};
+
+}  // namespace
+
+// Makes sure that when a WebContents is replaced, it notifies its observers.
+TEST_F(WebContentsImplTest, NotifiesOnReplacement) {
+  WebContents* other_contents = contents()->Clone();
+
+  MockWebContentsObserver observer(contents());
+  EXPECT_CALL(observer, WebContentsReplaced(contents(), other_contents));
+  contents()->OnReplaced(other_contents);
+
+  delete other_contents;
+}
+
 }  // namespace content