Remove the allow-displaying-mixed-content setting from Blink.

third_party/WebKit/Source/core/loader/MixedContentChecker.cpp

Index: third_party/WebKit/Source/core/loader/MixedContentChecker.cpp
diff --git a/third_party/WebKit/Source/core/loader/MixedContentChecker.cpp b/third_party/WebKit/Source/core/loader/MixedContentChecker.cpp
index 639a7fd273737b48434ac3b0496d3774e76f56d4..1b46299fa7ce7f7c464ed899fee268b553f18f51 100644
--- a/third_party/WebKit/Source/core/loader/MixedContentChecker.cpp
+++ b/third_party/WebKit/Source/core/loader/MixedContentChecker.cpp
@@ -217,7 +217,8 @@ bool MixedContentChecker::shouldBlockFetch(LocalFrame* frame, WebURLRequest::Req
 
     switch (contextType) {
     case WebMixedContent::ContextType::OptionallyBlockable:
-        allowed = !strictMode && client->allowDisplayingInsecureContent(settings && settings->allowDisplayOfInsecureContent(), url);
+        client->passiveInsecureContentFound(url);

[Mike West, 2016/08/31 09:46:51]

It looks like `ContentSettingsObserver::passiveInsecureContentFound` would end
up changing the UI. I think this changes the behavior in ways we don't want.
That is, strict mode should block the content without degrading the omnibox
display.

The current code doesn't call up to the client at all if we're in strict mode.
Would it be reasonable to move this call into the `if (allowed)` block? (Perhaps
simplifying that to `if (!strictMode)`?

[carlosk, 2016/09/02 23:47:42]

ContentSettingsObserver::passiveInsecureContentFound (previously known as
allowDisplayingInsecureContent) is currently only reporting histograms so I
don't see any UI change as a consequence of that call. Did I miss something?
Moving that call inside the if-block would change the current behavior: the
histograms reporting I mentioned above would only happen if mixed content was
allowed here, whereas right now they would be recorded even if not.

Also the `allowed` variable must be set because it is accessed further down this
method hence why I didn't do that simplification.

[Mike West, 2016/09/05 10:01:51]

Got it, thanks for the explanation. Blink LGTM.

+        allowed = !strictMode;
         if (allowed)
             client->didDisplayInsecureContent();
         break;