[Blink] Don't center images in Android WebViews

third_party/WebKit/Source/core/html/ImageDocument.cpp

Index: third_party/WebKit/Source/core/html/ImageDocument.cpp
diff --git a/third_party/WebKit/Source/core/html/ImageDocument.cpp b/third_party/WebKit/Source/core/html/ImageDocument.cpp
index 5a716aa9331096f846fcd571083c1446490fd60f..0adad97975ba5e1d8bd39ef786f0c9701dfeb259 100644
--- a/third_party/WebKit/Source/core/html/ImageDocument.cpp
+++ b/third_party/WebKit/Source/core/html/ImageDocument.cpp
@@ -48,6 +48,7 @@
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/loader/resource/ImageResource.h"
+#include "core/page/Page.h"
 #include "platform/HostWindow.h"
 #include "wtf/text/StringBuilder.h"
 #include <limits>
@@ -594,7 +595,9 @@ ImageResource* ImageDocument::cachedImageResourceDeprecated() {
 }
 
 bool ImageDocument::shouldShrinkToFit() const {
-  return frame()->isMainFrame();
+  bool isWrapContentWebView =
+      page() ? page()->settings().getForceZeroLayoutHeight() : false;

[pdr., 2017/01/19 03:17:32]

Is getForceZeroLayoutHeight causing the height to be zero which causes the
infinite loop of window size changes? Or is getForceZeroLayoutHeight only used
as a "isWebview" check?

[aelias_OOO_until_Jul13, 2017/01/19 03:53:07]

It's used as isWebView (_in_WRAP_CONTENT_mode).  The reason in the first place
for the settings is because a lot of the rest of Blink layout is prone to the
same infinite loop of window size changes, and forcing the layout height to zero
proves a nice universal mitigation.  The code in this file uses visible height
instead of layout height so it needs a more explicit check.

[pdr., 2017/01/19 05:04:27]

Could we just add an isWebView() function instead of getWideViewportQuirkEnabled
and getForceZeroLayoutHeight? I see several of these calls throughout Blink.
That's out of scope for this patch though.

Can we add a comment here though? Something similar to the change description
like "WebView automatically resizes to match the contents which will cause an
infinite loop as the contents then resize to match the window. To prevent this,
we disable shrinking to fit for WebViews"

+  return frame()->isMainFrame() && !isWrapContentWebView;
 }
 
 DEFINE_TRACE(ImageDocument) {