Add support for webViewContainingBlockedImage.

ios/web/public/test/earl_grey/web_view_matchers.mm

Index: ios/web/public/test/earl_grey/web_view_matchers.mm
diff --git a/ios/web/public/test/earl_grey/web_view_matchers.mm b/ios/web/public/test/earl_grey/web_view_matchers.mm
index d89d836c220bff09ce5cfd64596e83e23df2c83d..b6c4ac19251ff1b9e03e912b4ef26dd29f8d7a4d 100644
--- a/ios/web/public/test/earl_grey/web_view_matchers.mm
+++ b/ios/web/public/test/earl_grey/web_view_matchers.mm
@@ -102,6 +102,58 @@ id<GREYMatcher> webViewContainingText(std::string text, WebState* web_state) {
                     nil);
 }
 
+id<GREYMatcher> webViewContainingBlockedImage(std::string image_id,

[Eugene But (OOO till 7-30), 2016/08/24 14:39:27]

Now I think I understand why you require size to pass. You don't want to pass
both id and url.

Passing only URL object can do the trick if you use this CSS selector to find
the image:

document.querySelector('img[src*="<url>"]')

[justincohen, 2016/08/24 20:47:52]

Acknowledged.

+                                              CGSize expected_size,

[Eugene But (OOO till 7-30), 2016/08/24 14:32:45]

Is there a reason why you can non download image in matcher? Requiring clients
to know |expected_size| seems like an inconvenient approach.

[justincohen, 2016/08/24 20:47:51]

Since no one else uses this?

+                                              WebState* web_state) {
+  MatchesBlock matches = ^BOOL(WKWebView*) {
+    __block BOOL did_succeed = NO;
+    NSDate* deadline =
+        [NSDate dateWithTimeIntervalSinceNow:testing::kWaitForUIElementTimeout];
+    while (([[NSDate date] compare:deadline] != NSOrderedDescending) &&
+           !did_succeed) {
+      NSString* const kGetElementAttributesScript = [NSString
+          stringWithFormat:@"var image = document.getElementById('%@');"
+                           @"var imageHeight = image.height;"
+                           @"var imageWidth = image.width;"
+                           @"JSON.stringify({"
+                           @"  height:imageHeight,"
+                           @"  width:imageWidth"
+                           @"});",
+                           base::SysUTF8ToNSString(image_id)];
+      std::unique_ptr<base::Value> value = ExecuteScript(
+          web_state, base::SysNSStringToUTF8(kGetElementAttributesScript));
+      std::string result;
+      if (value && value->GetAsString(&result)) {
+        NSString* evaluationResult = base::SysUTF8ToNSString(result);

[Eugene But (OOO till 7-30), 2016/08/24 14:32:45]

s/evaluationResult/evaluation_result since it's C function which should follow
C++ Style Guide.

Same for imageAttributesAsData, imageAttributes

[justincohen, 2016/08/24 20:47:52]

Done.

+        NSData* imageAttributesAsData =
+            [evaluationResult dataUsingEncoding:NSUTF8StringEncoding];
+        NSDictionary* imageAttributes =
+            [NSJSONSerialization JSONObjectWithData:imageAttributesAsData
+                                            options:0
+                                              error:nil];
+        CGFloat height = [imageAttributes[@"height"] floatValue];
+        CGFloat width = [imageAttributes[@"width"] floatValue];
+        did_succeed =
+            (height < expected_size.height && width < expected_size.width);
+      }
+      base::test::ios::SpinRunLoopWithMaxDelay(
+          base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
+    }
+    return did_succeed;
+  };
+
+  DescribeToBlock describe = ^(id<GREYDescription> description) {
+    [description appendText:@"web view blocking resource with id "];
+    [description appendText:base::SysUTF8ToNSString(image_id)];
+  };
+
+  return grey_allOf(webViewInWebState(web_state),
+                    [[[GREYElementMatcherBlock alloc]
+                        initWithMatchesBlock:matches
+                            descriptionBlock:describe] autorelease],
+                    nil);
+}
+
 id<GREYMatcher> webViewCssSelector(std::string selector, WebState* web_state) {
   MatchesBlock matches = ^BOOL(WKWebView*) {
     std::string script = base::StringPrintf(kTestCssSelectorJavaScriptTemplate,