8275138: WebView: UserAgent string is empty for first request

[kevinrushforth]

The failure was caused by a change that was done in connection with the WebKit 610.2 update, JDK-8259635. The FrameLoaderClient::userAgent function was changed in WebKit itself to be a const method in WebKit 610.2. We override that method in FrameLoaderClientJava to return the user agent string, which is done by reading the user agent from an instance of the Page class. FrameLoaderClientJava has a m_page field that is lazily initialized whenever it is needed. This lazy initialization can no longer be done from the userAgent method, since it is const, as can be seen from this change that was done as part of WebKit 610.2:

--- a/modules/javafx.web/src/main/native/Source/WebKitLegacy/java/WebCoreSupport/FrameLoaderClientJava.cpp
+++ b/modules/javafx.web/src/main/native/Source/WebKitLegacy/java/WebCoreSupport/FrameLoaderClientJava.cpp
-String FrameLoaderClientJava::userAgent(const URL&)
+String FrameLoaderClientJava::userAgent(const URL&) const
 {
-    return page()->settings().userAgent();
+    if (!m_page)
+        return emptyString();
+    return m_page->settings().userAgent();
 }

Formerly, if the m_page field was uninitialized, FrameLoaderClient::userAgent would have initialized it by the call to the page() function, but since it is now const we can't do that. This means that the user agent string will be empty until some other method is called that initializes the m_page field.

The fix is to initialize that field when the WebPage is created. We can't do it in the constructor, since the needed reference to the Page class isn't yet available, so I added an init method that is called from WebPage::twkInit.

I added a new unit test that fails without the fix and passes with the fix.

---

Progress

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Issue

• JDK-8275138: WebView: UserAgent string is empty for first request

Reviewers

• Ajit Ghaisas (@aghaisas - Reviewer)
• Ambarish Rapte (@arapte - Reviewer)

Reviewing

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[kevinrushforth]

/reviewers 2

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[openjdk]

@kevinrushforth
The number of required reviews for this PR is now set to 2 (with at least 1 of role reviewers).

[mlbridge]

Webrevs

• 00: Full (fba7ffcb)

[aghaisas]

The fix looks fine. I built and tested on mac.
The new test fails without the fix and passes with it.

[arapte]

looks good to me too.

[openjdk]

@kevinrushforth This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8275138: WebView: UserAgent string is empty for first request

Reviewed-by: aghaisas, arapte

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[kevinrushforth]

/integrate

[openjdk]

Going to push as commit d6f78e2.

[openjdk]

@kevinrushforth Pushed as commit d6f78e2.

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