Adding support for controlling the global sRGB SkColor switch.

Frontend change: https://codereview.chromium.org/1900233002/

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1902143002

Review URL: https://codereview.chromium.org/1902143002

tools/skiaserve/Request.cpp

@@ -9,6 +9,7 @@
 
 #include "SkPictureRecorder.h"
 #include "SkPixelSerializer.h"
+#include "SkPM4fPriv.h"
 #include "picture_utils.h"
 
 using namespace sk_gpu_test;
@@ -186,6 +187,11 @@ bool Request::setColorMode(int mode) {
     return enableGPU(fGPUEnabled);
 }
 
+bool Request::setSRGBMode(bool enable) {
+    gTreatSkColorAsSRGB = enable;
+    return true;
+}
+
 bool Request::enableGPU(bool enable) {
     if (enable) {
         SkSurface* surface = this->createGPUSurface();
@@ -238,6 +244,7 @@ SkData* Request::getJsonOps(int n) {
     root["mode"] = Json::Value(fGPUEnabled ? "gpu" : "cpu");
     root["drawGpuBatchBounds"] = Json::Value(fDebugCanvas->getDrawGpuBatchBounds());
     root["colorMode"] = Json::Value(fColorMode);
+    root["srgbMode"] = Json::Value(gTreatSkColorAsSRGB);
     SkDynamicMemoryWStream stream;
     stream.writeText(Json::FastWriter().write(root).c_str());
 

tools/skiaserve/Request.h

@@ -42,6 +42,7 @@ struct Request {
     SkBitmap* getBitmapFromCanvas(SkCanvas* canvas);
     bool enableGPU(bool enable);
     bool setColorMode(int mode);
+    bool setSRGBMode(bool enable);
     bool hasPicture() const { return SkToBool(fPicture.get()); }
     int getLastOp() const { return fDebugCanvas->getSize() - 1; }
 

tools/skiaserve/skiaserve.cpp

@@ -41,6 +41,7 @@ public:
         fHandlers.push_back(new BatchesHandler);
         fHandlers.push_back(new BatchBoundsHandler);
         fHandlers.push_back(new ColorModeHandler);
+        fHandlers.push_back(new SRGBModeHandler);
     }
 
     ~UrlManager() {

tools/skiaserve/urlhandlers/SRGBModeHandler.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "UrlHandler.h"
+
+#include "microhttpd.h"
+#include "../Request.h"
+#include "../Response.h"
+
+using namespace Response;
+
+bool SRGBModeHandler::canHandle(const char* method, const char* url) {
+    static const char* kBasePath = "/srgbMode/";
+    return 0 == strcmp(method, MHD_HTTP_METHOD_POST) &&
+           0 == strncmp(url, kBasePath, strlen(kBasePath));
+}
+
+int SRGBModeHandler::handle(Request* request, MHD_Connection* connection,
+                             const char* url, const char* method,
+                             const char* upload_data, size_t* upload_data_size) {
+    SkTArray<SkString> commands;
+    SkStrSplit(url, "/", &commands);
+
+    if (commands.count() != 2) {
+        return MHD_NO;
+    }
+
+    int enable;
+    if (1 != sscanf(commands[1].c_str(), "%d", &enable)) {
+        return MHD_NO;
+    }
+
+    bool success = request->setSRGBMode(enable);
+    if (!success) {
+        return SendError(connection, "Unable to set requested mode");
+    }
+    return SendOK(connection);
+}

tools/skiaserve/urlhandlers/UrlHandler.h

@@ -141,3 +141,16 @@ public:
                const char* url, const char* method,
                const char* upload_data, size_t* upload_data_size) override;
 };
+
+/**
+ * Controls the global sRGB flag (is SkColor treated as sRGB or not).
+ * Posting to /srgbMode/0 causes SkColor to be linear, /colorMode/1
+ * causes SkColor to be sRGB;
+ */
+class SRGBModeHandler : public UrlHandler {
+public:
+    bool canHandle(const char* method, const char* url) override;
+    int handle(Request* request, MHD_Connection* connection,
+               const char* url, const char* method,
+               const char* upload_data, size_t* upload_data_size) override;
+};