DevTools: improve preview content type detection

1. Preview will now attempt to deduce content type from the mime type
   and not the resource type. Images loaded via fetch will now be
   properly shown.
2. "Response" type will now recognize SVG as a text file and show the
   source code.

Bug: 688563
Change-Id: Ie0ec2e46314e0d71ecc69e0517984bcdb3a2f755
Reviewed-on: https://chromium-review.googlesource.com/837731Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Eugene Ostroukhov <eostroukhov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526076}

third_party/WebKit/LayoutTests/http/tests/devtools/network/network-choose-preview-view-expected.txt

@@ -105,10 +105,10 @@ Binary Image File
 Testing with MimeType: image/png, and StatusCode: 200
 Content: Bin**NULL**ary
 File**NULL****NULL**
 
-ResourceType(xhr): SearchableView > widget vbox
-ResourceType(fetch): SearchableView > widget vbox
-ResourceType(document): SearchableView > widget vbox
-ResourceType(other): SearchableView > widget vbox
+ResourceType(xhr): widget vbox image-view
+ResourceType(fetch): widget vbox image-view
+ResourceType(document): widget vbox image-view
+ResourceType(other): widget vbox image-view
 
 Binary Blank Image File
 Testing with MimeType: image/png, and StatusCode: 200

third_party/WebKit/Source/devtools/front_end/network/RequestResponseView.js

@@ -47,11 +47,17 @@ Network.RequestResponseView = class extends UI.VBox {
    * @return {boolean}
    */
   static _hasTextContent(request, contentData) {
-    if (request.resourceType().isTextType())
+    var mimeType = request.mimeType;
+    var resourceType = Common.ResourceType.fromMimeType(mimeType);
+    if (resourceType === Common.resourceTypes.Other)
+      resourceType = request.contentType();
+    if (resourceType === Common.resourceTypes.Image)
+      return mimeType.startsWith('image/svg');
+    if (resourceType.isTextType())
       return true;
     if (contentData.error)
       return false;
-    if (request.resourceType() === Common.resourceTypes.Other)
+    if (resourceType === Common.resourceTypes.Other)
       return !!contentData.content && !contentData.encoded;
     return false;
   }

third_party/WebKit/Source/devtools/front_end/source_frame/PreviewFactory.js

@@ -13,6 +13,17 @@ SourceFrame.PreviewFactory = class {
     if (!content)
       return new UI.EmptyWidget(Common.UIString('Nothing to preview'));
 
+    var resourceType = Common.ResourceType.fromMimeType(mimeType);
+    if (resourceType === Common.resourceTypes.Other)
+      resourceType = provider.contentType();
+
+    switch (resourceType) {
+      case Common.resourceTypes.Image:
+        return new SourceFrame.ImageView(mimeType, provider);
+      case Common.resourceTypes.Font:
+        return new SourceFrame.FontView(mimeType, provider);
+    }
+
     var parsedXML = SourceFrame.XMLView.parseXML(content, mimeType);
     if (parsedXML)
       return SourceFrame.XMLView.createSearchableView(parsedXML);
@@ -22,19 +33,11 @@ SourceFrame.PreviewFactory = class {
     if (parsedJSON && typeof parsedJSON.data === 'object')
       return SourceFrame.JSONView.createSearchableView(/** @type {!SourceFrame.ParsedJSON} */ (parsedJSON));
 
-    var resourceType = provider.contentType() || Common.resourceTypes.Other;
-
     if (resourceType.isTextType()) {
       var highlighterType = mimeType.replace(/;.*/, '');  // remove charset
       return SourceFrame.ResourceSourceFrame.createSearchableView(provider, highlighterType);
     }
 
-    switch (resourceType) {
-      case Common.resourceTypes.Image:
-        return new SourceFrame.ImageView(mimeType, provider);
-      case Common.resourceTypes.Font:
-        return new SourceFrame.FontView(mimeType, provider);
-    }
     return null;
   }
 };