Refactor ImageDocument::UpdateImageStyle()

This moves the determination of the mouse cursor to a separate method,
dropping the associated state in the process.
Drop the ShouldShrinkToFit() check in ImageLoaded(). This will have no
direct effect at the moment, but will aid a future CL.

Bug: 844743
Change-Id: Iae464e999668f7f77b13e03018e801c3885fb6f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461268
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815246}

third_party/blink/renderer/core/html/image_document.cc

@@ -204,7 +204,6 @@ ImageDocument::ImageDocument(const DocumentInit& initializer)
       did_shrink_image_(false),
       should_shrink_image_(ShouldShrinkToFit()),
       image_is_loaded_(false),
-      style_mouse_cursor_mode_(kDefault),
       shrink_to_fit_mode_(GetFrame()->GetSettings()->GetViewportEnabled()
                               ? kViewport
                               : kDesktop) {
@@ -394,11 +393,17 @@ void ImageDocument::ImageClicked(int x, int y) {
 
 void ImageDocument::ImageLoaded() {
   image_is_loaded_ = true;
+  UpdateImageStyle();
+}
 
-  if (ShouldShrinkToFit()) {
-    // The checkerboard background needs to be inserted.
-    UpdateImageStyle();
-  }
+ImageDocument::MouseCursorMode ImageDocument::ComputeMouseCursorMode() const {
+  if (!image_is_loaded_)
+    return kDefault;
+  if (shrink_to_fit_mode_ != kDesktop || !ShouldShrinkToFit())
+    return kDefault;
+  if (ImageFitsInWindow())
+    return kDefault;
+  return should_shrink_image_ ? kZoomIn : kZoomOut;
 }
 
 void ImageDocument::UpdateImageStyle() {
@@ -409,36 +414,14 @@ void ImageDocument::UpdateImageStyle() {
     if (shrink_to_fit_mode_ == kViewport)
       image_style.Append("max-width: 100%;");
     image_style.Append("margin: auto;");
-
-    if (image_is_loaded_) {
-      MouseCursorMode new_cursor_mode = kDefault;
-
-      if (shrink_to_fit_mode_ != kViewport) {
-        // In desktop mode, the user can click on the image to zoom in or out.
-        DCHECK_EQ(shrink_to_fit_mode_, kDesktop);
-        if (ImageFitsInWindow()) {
-          new_cursor_mode = kDefault;
-        } else {
-          new_cursor_mode = should_shrink_image_ ? kZoomIn : kZoomOut;
-        }
-      }
-
-      // The only thing that can differ between updates is
-      // the type of cursor being displayed.
-      if (new_cursor_mode == style_mouse_cursor_mode_) {
-        return;
-      }
-      style_mouse_cursor_mode_ = new_cursor_mode;
-
-      if (shrink_to_fit_mode_ == kDesktop) {
-        if (style_mouse_cursor_mode_ == kZoomIn)
-          image_style.Append("cursor: zoom-in;");
-        else if (style_mouse_cursor_mode_ == kZoomOut)
-          image_style.Append("cursor: zoom-out;");
-      }
-    }
   }
 
+  MouseCursorMode cursor_mode = ComputeMouseCursorMode();
+  if (cursor_mode == kZoomIn)
+    image_style.Append("cursor: zoom-in;");
+  else if (cursor_mode == kZoomOut)
+    image_style.Append("cursor: zoom-out;");
+
   image_element_->setAttribute(html_names::kStyleAttr,
                                image_style.ToAtomicString());
 }

third_party/blink/renderer/core/html/image_document.h

@@ -57,6 +57,10 @@ class CORE_EXPORT ImageDocument final : public HTMLDocument {
  private:
   DocumentParser* CreateParser() override;
 
+  enum MouseCursorMode { kDefault, kZoomIn, kZoomOut };
+  // Compute the state of the mouse cursor in the image style.
+  MouseCursorMode ComputeMouseCursorMode() const;
+
   // Calculates how large the div needs to be to properly center the image.
   int CalculateDivWidth();
 
@@ -83,10 +87,6 @@ class CORE_EXPORT ImageDocument final : public HTMLDocument {
   // Whether the image has finished loading or not
   bool image_is_loaded_;
 
-  // Desktop: State of the mouse cursor in the image style
-  enum MouseCursorMode { kDefault, kZoomIn, kZoomOut };
-  MouseCursorMode style_mouse_cursor_mode_;
-
   enum ShrinkToFitMode { kViewport, kDesktop };
   ShrinkToFitMode shrink_to_fit_mode_;
 

third_party/blink/web_tests/http/tests/security/contentSecurityPolicy/image-document-default-src-none-expected.txt

@@ -2,4 +2,6 @@ CONSOLE ERROR: Refused to apply inline style because it violates the following C
 
 CONSOLE ERROR: Refused to apply inline style because it violates the following Content Security Policy directive: "default-src 'none'". Either the 'unsafe-inline' keyword, a hash ('sha256-VPZ2mdsWWlqXOFgt1tAllbbJhG8t9bh6emP1o9GwJxY='), or a nonce ('nonce-...') is required to enable inline execution. Note also that 'style-src' was not explicitly set, so 'default-src' is used as a fallback.
 
+CONSOLE ERROR: Refused to apply inline style because it violates the following Content Security Policy directive: "default-src 'none'". Either the 'unsafe-inline' keyword, a hash ('sha256-VPZ2mdsWWlqXOFgt1tAllbbJhG8t9bh6emP1o9GwJxY='), or a nonce ('nonce-...') is required to enable inline execution. Note also that 'style-src' was not explicitly set, so 'default-src' is used as a fallback.
+
 Ensure that we don't crash when loading an ImageDocument that sets CSP headers